Particles of nature can be put in two large distinct groups- Bosons and Fermions, based on their overall spin. Bosons correspond to Bose-Einstein statistics and possess integer spin such as 0, 1, 2 while Fermions correspond to Fermi-Dirac statistics and exhibit odd half integer spin such as ½, 3/2 so on. Fermions cannot exist in same quantum state at same place at the same time. This is known as Pauli Exclusion Principle. Bosons on the other hand can and do exist at same place, at the same time in same quantum state. Gluon, Photon, W, Z, Higgs and still hypothetical Graviton are Bosons. W and Z Bosons have spin of 1 and carry the weak force field which holds nucleons together to form atomic nucleus. Gluons exhibit a spin of 1 and carry strong force field which keeps Quarks together to form Protons and Neutrons. Photons also have a spin of 1 and carry Electromagnetic field responsible for Electromagnetism. Higgs Boson has a spin of 0 and it carries the field responsible for mass of particles. Particles become massive when they interact with the Higgs field. Particles such as Photons pass straight through this field without interacting and therefore have zero mass. Gravitons are supposed to have a spin of 2 and carry the field responsible for Gravity. Of these field carrying Bosons only W Boson carries charge. Charge carried by W Boson has a value of -1. Photon and Gluon are massless because they are not affected by Higgs field. Gravitons also are predicted to be massless. W Boson carries mass of 80.4 GeV/c2, Z Boson Carries mass of 91.2 GeV/c2 and Higgs Boson carries mass of 125.3 GeV/c2. Apart from these there are composite Bosons such as Mesons. One Quark and one Antiquark held together by strong field is named Meson. Both constituting Quarks have odd half integer spin and therefore are Fermions, giving Meson an integer overall spin of either 0 or 1. Mesons are very short lived. They quickly decay into more fundamental particles. Charged Mesons decay into Electrons and Neutrinos. Sometimes they decay into intermediate particles which then further decay to Electrons and Neutrinos. Pion, Kaon and J/Ψ are Mesons. Atomic nucleus can be a Fermion or Boson depending on number of Protons and Neutrons contained. If the number is even then it’s a Boson, otherwise it is a Fermion. Depending on whether it is a Boson or Fermion, some strange properties are observed in Elements.
Quark and Lepton are Fermions. So far we know of six Quarks named Up, Down, Charm, Strange, Top and Bottom, all having spin of 1/2. There is an anti particle pair for each one of them. They all carry fractional charge and they all have mass. Up Quark carries charge of +2/3 and Down Quark carries charge of -1/3. A Proton is two Up Quarks and a Down Quark held together by three Gluons. Since overall spin is half integer, Proton is a type of composite Fermion classified under the name of Baryon- particles made of three Quarks. Before 1987 it was thought that spin of Protons is a resultant of spin of its three constituent Quarks. But the 1987 European Muon Collaboration test indicated that this was not correct. It turned out that Quarks contribute only a very little, 25% at most to the overall spin of Protons. Scientists at RHIC have come up with conclusive evidence that contribution of Gluons to overall spin of Protons is almost same as that of Quarks, a value in the range of 20% to 30% of total Proton spin. Remaining spin might be coming from orbital angular momentum of Quark-Gluon system buzzing around confined by the weak force. Confinement might also be contributing to mass of Proton apart from the Higgs field contribution. Missing spin problem was named Proton spin Crisis. Neutron is another composite Fermion made of two Down Quarks and one Up Quark held together by three Gluons. Because it is made of three Quarks, Neutron also is a Baryon. Baryons are strongly interactive in nature. Protons can exist freely for extremely long time, free Neutrons on the other hand have a mean lifetime of 881.5±1.5 s. At the end of life, free Neutrons decay into Proton, Electron and Electron Antineutrino. Nucleus of a Carbon-13 atom is also a composite Fermion as it is formed by six Protons and seven Neutrons, making overall spin odd half integer.
Electron, Electron Neutrino, Muon, Muon Neutrino, Tau and Tau Neutrino are six known Leptons with a spin value of 1/2. Electron, Muon and Tau carry a charge of -1 while the three Neutrinos are neutral. Antiparticles of all six Lepton are also Fermionic. Leptons are weakly interactive Fermions and have lower mass than Baryons, Electron and Electron Neutrino being least massive with mass of .511 MeV/c2 and less than 2.2 eV/c2 respectively. Electrons are stable, Muons have lifetime 2.197 microseconds, Tau have lifetime of .2906 Picoseconds while lifetime of the three Neutrinos is unknown. Composite particles made of Quarks, Antiquarks and Gluons are classified as Hadrons. Fermionic Baryons are made of three Quarks and Bosonic Mesons are made of one Quark and one Antiquark and therefore are Hadrons. Baryonic Hadrons can be put in three groups- Baryons made of one type of Quark, Baryons made of two types of Quark and Baryons made of three types of Quark. Baryonic Protons and Neutrons are most common Hadrons in nature. Pion and Kaon are confirmed Mesonic Hadrons. All Mesons are highly unstable and quickly decay into other more stable particles such as Electrons.
Exotic Baryons and Exotic Mesons are composite particles grouped as Exotic Hadrons. Some of them are confirmed to exist while some other still remain hypothetical. Composite particles made of four or more Quarks and Antiquarks and Gluons are collectively called Exotic Baryons. As of August 2015, two Pentaquarks made of four Quarks and an Antiquark have been discovered at Large Hadron Collider. Dibaryon or Hexaquark and Skyrmion are exotic Baryons predicted to exist but have not been detected yet. Glueballs, composite of Gluons and Tetraquark are exotic Meson candidates. Z(4430) is a charged Tetraquark whose existence is confirmed by LHCb experiment.
For Every particle in standard model an anti particle exists. Anti particles are same as particles except for their charge which is opposite. For example nucleus of antiatom is negatively charged but the Positrons whirling around are positively charged making the antiatom neutral. Particle and anti particle if brought together, annihilate each other converting into energy. If all matter in Universe is replaced with #Antimatter and flow of time is reversed, the anti matter world thus formed will be a mirror image of our everyday matter world with identical nature. In science it is known as Charge-Parity-Time Reversal symmetry or CPT symmetry. Matter and Antimatter particles are always produced in pair. Equal number of particles and anti particles should have been created at Big Bang. Then why there is so little anti matter in known Universe against amount of Matter? This is one of the questions LHC will try to answer in its future runs. Scientists have hints that laws of nature do not apply equally to Matter and Antimatter. A very small amount of matter may have survived mutual annihilation during early days of Universe causing it to be as we find it today. Using ALICE experiment a team of scientists at CERN confirmed in August 2015 that Matter and Antimatter indeed are perfect mirror of each other and should completely annihilate one another whenever they meet. Baryon Antibaryon symmetry experiment gave same conclusion. Standard model is incomplete. It still cannot explain Gravity and Dark Matter. Experiments at LHC are aimed at solving these problems. Scientists there will try to detect Graviton, particle supposed to carry Gravitational field and weakly interactive massive particles or WIMPS which are supposed to compose Dark Matter. Detection of either one of these will be an epochal moment for humankind.
While Ernest Rutherford, Hans Geiger and Ernest Marsden were bombarding Gold foils with Alpha particles in 1909 leading to the discovery of atomic nucleus, Chemists were finishing analysis of gas emission spectrum. When light obtained from heating up gases in a glass tube was passed through a prism, it formed distinct lines of light of different colors for example in case of Hydrogen, Red, Blue/Cyan and Violet colored lines were obtained. Niels Bohr, by putting together Einstein’s theory of light and J.J. Balmer's empirical formula came up with an explanation in 1913. He figured that Electrons absorb energy when gas is heated up and leap to higher energy orbits around the nucleus, but they only leap to certain orbits after absorbing specific amount of energy. When cooled down the Electrons emit energy in specific amounts termed as Quanta and leap in to lower energy orbits. We obtain distinct lines of different colored light because electrons absorb and emit energy in certain amounts. Electrons can only have certain amounts of energy, not just any value. This explanation also rescued Rutherford’s atomic model because now it was understood why Electrons did not get pulled into the nucleus given their opposite charges.
Balmer's formula
Here RH is Rydberg constant for Hydrogen, n1=2 and n2 greater than n1
Louis-Victor De Broglie after intensely studying wave particle duality of light pioneered by Max Planck and Albert Einstein, presented his famous hypothesis in 1924 stating not only light has both wave and particle properties but particles such as Electrons too should have both wave and particle like characteristics. De Broglie called the wave associated to a particle, matter wave. He showed that wave, characteristic to a particular particle should have a wavelength of
λ=h/p
Where h=Planck’s constant having a value of 6.626068*10-34m2kg/s and p=momentum of the particle.
Werner Heisenberg et al presented matrix mechanics to describe wave nature of particles in 1925. In 1926 Erwin Schrodinger created wave mechanics in an attempt to describe matter waves. Latter Schrodinger showed that matrix mechanics and wave mechanics are equivalent. Max born showed a statistical version of wave function and pointed that solution to Schrodinger’s wave equation for particles gives probability of finding a subatomic particle like an Electron at a particular location, it doesn't describes a smeared out Electron as Schrodinger himself had thought. By 1927 George Paget Thomson in UK and Clinton Davisson and Lester Germer in US had experimental evidence of wave like properties of Electrons. They were conducting their experiments with Electron beams although with different purposes but found similar diffraction patterns indicating wave like nature of Electrons. These were very first experimental support for De Broglie’s matter waves, 3 years after they were presented. Latter while calculating probability of finding an Electron at different locations using Schrodinger’s wave equation, scientists found a definite probability of finding the Electron on other side of the detector screen. Further they found a certain probability of finding an Electron on other side of a thick wall and even a mountain. This surprising probability is described as Quantum Tunneling and it is real. It is thought that Electron borrows energy required to get through solid wall from future and returns that energy once it is on the other side. As bizarre as it may sound but most probably, that’s how it is. Scientists are harnessing this property of Electrons in creating faster and smaller transistors and Quantum Computers. Transistors utilizing Quantum Tunneling will be much smaller and much faster than the smallest transistors we have today like those 11nm CMOS transistors.
After the equivalence of Matrix and wave mechanics was established, Jordan in Gottingen University and Paul Dirac in Cambridge university merged these two different ways of representing a matter wave mathematically and came up with what became known as transformation theory. Heisenberg while pondering over the papers of Jordan and Dirac figured that more precisely the position of a subatomic particle is known, less precisely its momentum can be known. In 1927, He came up with a mathematical expression to quantize this uncertainty.
ΔxΔp ≥ h/4Π
Where Δx= Standard deviation of position, Δp= Standard deviation of momentum, h= Planck’s constant
Same uncertainty holds for certain other pair of variables too such as energy and time for which the particle can have that energy. In order to explain this result Heisenberg thought up an experiment using Gamma ray microscope. Gamma rays have higher frequency than Electrons and therefore when used to determine position of Electron it will significantly change the direction of motion of Electron upon impact. Even visible light when shone to find the location of Electron will alter its velocity by some amount as energy of photon is comparable to energy of an Electron, leading Heisenberg to conclude that uncertainty is inbuilt into nature itself. As a matter of fact, with Uncertainty principle the predictions of Quantum Mechanics became consistent. Of ‘course the principle has been verified in many experiments since 1927, most common of them being the slit experiment.
In 1801 Thomas Young took up the task of measuring light’s wavelength. He used a paper card to split a single pinhole beam of sunlight into two to carry out his experiment. Latter the practice of using two narrowly separated slits caught on. Italian physicists Pier Giorgio Merli, Gian Franco Missiroli and Giulio Pozzi did the double slit experiment with a single Electron in 1974. They found an interference pattern on the detector screen, kind of pattern which is created by waves, proving the predictions of Quantum Mechanics. Latter on Scientists discovered that when they look at the Electron fired from Electron gun, it formed a particle like pattern on detector screen and when they did not look, it formed a wave interference pattern. But, how a single Electron can form wave interference pattern? Although the predictions of Quantum Mechanics were verified, nobody had any idea, how. This mystery is still without a good explanation. In more recent versions of this experiment, Scientists observed the Electron after it crossed the slits. To their surprise they found that when they look, the Electron formed a particle like pattern and when they didn’t, it again formed a wave like pattern. How is that possible? Nobody knows the answer even today, but we do know now that Bohr was right. That, act of observation does really changes behavior of a particle. In addition, these observations also gave support to Heisenberg’s Uncertainty Principle. These experiments supported probability wave nature of Electron as predicted by Schrodinger’s wave equation and supported De Broglie’s matter waves or wave particle duality. We know now that the Electron can be in many positions at the same time or wave like if we are not looking at it, a Quantum Mechanical phenomena known as Quantum Superposition, and takes a particular position or behaves particle like if we do look at it.
Albert Einstein had other ideas about Quantum Mechanics. He and two of his colleagues Boris Podolsky and Nathan Rosen came up with a prediction of Quantum Mechanics in 1935, which he thought cannot be true, leading to his declaration that Quantum Mechanics is not wrong but it is incomplete. That prediction was Quantum Entanglement. Einstein together with his colleagues said that according to Schrodinger’s wave equation and other principles of Quantum Mechanics if two fundamental particles share their source of origin then their properties will have to be linked in such a way that sum of measurements of their Quantum properties give the Quantum property of source particle no matter how far apart these two particles are. This can be possible only if an act of measurement on one of these entangled particles simultaneously affects the Quantum state of other particle thus keeping the sum total same as it would be for the Quantum state of the source particle. This indicates some form of communication between the two particles happening at speeds greater than speed of light, leading Einstein to conclude that the theory is incomplete and requires modifications. Bohr and his colleagues remained unmoved. In his 1964 paper, Irish Physicist John Stewart Bell came with an inequality to settle this dispute. According to the inequality if Einstein was right then Quantum Mechanics would not be just incomplete but it would be wrong. When experiment was done in 1972 by John Clauser and Stuart Freedman, Einstein was found wrong. Results of this experiment supported immediate communication between entangled particles. Latter in 1981-82 a more precise experiment was conducted by Alain Aspect which corroborated faster than light communication between entangled particles when an act of measurement is performed. Bell’s inequality indicated that if Quantum Entanglement was real then entangled particles will have higher correlation than classical physics would allow. Results obtained from experiments based on Bell’s inequality unequivocally indicated a higher correlation between entangled particles. Now scientists around world are harnessing this phenomenon for creating Quantum Computers and to achieve Teleportation.
Because of the uncertain nature of reality, first indicated by Heisenberg, we can’t say with certainty that empty space is without any energy-mass density. According to Quantum Mechanics there is a finite probability that empty space may have certain amount of energy as long as nobody observes it. More specifically, particles and antiparticles may originate from empty space in pairs and exist for a certain while before annihilating each other. Amount of time they exist for depends on their energy, as Quantum Mechanics predicts. More the energy, shorter the duration they exist for and vice versa. This prediction came to be known as quantum vacuum fluctuations of electromagnetic field and is inherent to space.
Hendrik Casimir while investigating the discrepancies in measurements done on colloids, using the theory of Fritz London concerning Van Der Walls forces, the forces that govern colloids, thought up an interesting event. In his 1948 paper he indicated that if two neutral conducting plates are placed about a micron apart in vacuum, then vacuum between plates could only create virtual photon pairs with very small wavelengths compared to vacuum around as kind of wavelengths that can exist between plates becomes limited because of the very short gap. This will cause a higher pressure due to impact of colliding virtual photons from vacuum around compared to pressure caused by virtual photons contained in between, causing plates to get pushed together. This became known as Casimir effect. Until recently, scientists were not able to create experimental conditions required to measure the force predicted by Casimir’s equation.
F=(Πhc/480L4)A
F= Force experienced by the plates, h= Planck’s constant, c= Speed of light, L= Gap between plates, A= Area of plates
In 1996, Steven Lamoreaux finally succeeded in creating lab conditions required for the experiment and found the experimental results to be within 5% of the value predicted by Casimir. By 2011, more accurate experimental confirmations have been achieved. Particles other than Photons also affect the plates but in magnitudes too small to be measurable by current technology. Effect of Bosons is attractive on the other hand effect of Fermions is repulsive. Existence of Casimir effect reveals a lot about nature of reality. For one it entails a broken Super symmetry, because it indicates absence of Fermionic photinos. Super symmetry has not been detected yet. It has other implications such as quantum gravity and about nature of space-time itself. Dynamic Casimir effect is a direct derivation and predicts that if the two plates move to and fro at speeds close to speed of light then virtual particles of vacuum may become real by converting energy of motion of plates.
LHC is a 26.659 kilometer ring of superconducting magnets cooled to -271.3˚C, a temperature even below the temperature of outer space which is -270.5˚C. It lies 50-175 meters underneath the surface. 1232 Dipole magnets, 15m in length are used for bending the beams and 392 quadrupole magnets, 5-7 meters long are used to focus them. Another type of magnets is used to bring beams closer, just prior to collision. Most of the 9593 magnets installed weigh over 27 tonnes and are made of Copper clad Niobium-Titanium and approximately 96 tonnes of superfluid Helium is required to maintain their operating temperature at -271.3˚C.
Pipes in which particle beams travel includes 48km of arc sections at 1.9K and 6km of straight sections at room temperature and are kept under ultra high vacuum even higher than the vacuum of intersteller void which is below 1.0133*10^-10 mbar or 10^-13 atmospheres.
Housing tunnel of beam pipes crosses the France-Switzerland border at 4 points and most of it lies within French territory. The 2 beam pipes run adjacent and parallel crossing at points where main particle detectors- ATLAS, CMS, ALICE and LHCb are located. ATLAS detector was used to find Higgs-Boson. Each detector serves a specific kind of detection. Beams travel in opposite direction within these pipes and are made to collide at the intersections at a staggering rate of 1 billion collisions per second. TOTEM,LHCfand moEDAL are the other 3 smaller detectors.
ATLAS Detector or #ATLASExperiment is equipped with Muon spectrometer, Magnet system, pixel detectors, transition radiation trackers, semiconductor tracker, electromagnetic calorimeter, and Hadronic calorimeter to record the trail of subatomic particles created in collisions. These trails are latter analyzed to obtain information about the subatomic particles that created them.
ATLAS stands for A Toroidal LHC apparatus. It is the largest detector at 46 meters long, 25 meter wide and 25 meter high and weighs 7000 tonnes. It is used to investigate #HiggsMechanism, #ExtraDimensions, micro black holes and particles constituting #darkmatter.
CMS is for compact muon solenoid and has same scientific goals as ATLAS detector but uses different technology and different magnet system. Its in the form of a multi layered cylinder and weighs more than 13000 tons. At inmost it comprises a particle tracker made entirely of silicon. After that electromagnetic calorimeter then hadronic calorimeter and then the solenoid magnet. At the outmost is the muon detectors and return yoke.
ALICE Stands for A large ion collider experiment. It is a heavy ion detector. It is designed to study Quark Gluon plasma which is created by the collision of Pb nuclei. Data obtained from these collisions could help understand the beginning of universe. One of the goals is to investigate why Protons and Neutrons weigh 100 times more than their constituent Quarks.
LHCb or Large Hadron Collider beauty experiment is used to investigate the slight differences between matter and antimatter by studying a type of particle called beauty quark or b quark. It includes a forward spectrometer and planar detectors.
Energy of 6.5TeV per proton has been achieved speeding the protons to 99.9999991% of speed of light which corresponds to a Lorentz factor of 7460, giving total collision energy of 13TeV.
Pb nuclei collisions create temperature of 5.5 Trillion degree Celsius for a fleeting while which is close to the temperature of Universe when it was only moments old.
As of 25 Nov 2015 first ion collision was achieved at 1PeV which is a record.
LHC Computing grid is designed to handle massive amount of data generated by collisions. It includes over 170 computing facilities across 36 countries and is the world’s largest computing grid. Over 30 petabytes of data is produced per year and over 6*10^15 proton-proton collisions has been analyzed by 2012.
Hadron in Large Hadron Collider stands for particles made of 3 Quarks such as Protons and Neutrons also known as Baryons and particles made of 1 Quark and 1 Antiquark also known as Mesons such as Pions.
Future runs of #LHC are aimed at testing Supersymmetry predictions, String theory and expanding our understanding of Higgs mechanism. Scientists will be looking for Sparticles and Gravitons and presence of higher spatial dimensions in data obtained from even higher energy collisions. They will also try to find dark matter and detect dark energy.
It took the effort of thousands of Scientists and Engineers over a period of 10 years and about $10 billion to build the LHC. For second run the estimated power consumption is 750 GWH per year which will cost in excess of 30 million dollars. Annual cost of running experiments comes up to be in excess of a billion dollars.
Watch how Proton beams are made to collide at such high energy levels in this video.
In Quantum computing, iterations are done using Quantum phenomena such as Superposition and Entanglement. Analogous to bits of classical computing we have Qubits in Quantum computing. In some cases spin of an Electron is used as Qubit as it is an inherent property and it fulfills the requirements for Qubit, apart from this certain properties of atom, ion and even a photon which is nothing but quanta of energy, can be used as Qubit. Electron spin can be assigned a value of up or down, but we can only calculate the probability of either state. Until measured, it could have both spin values at same time.
Scientists are constantly looking for new candidates for Qubit. A Qubit does not have absolute state of either 0 or 1 like a classical bit rather it is a superposition of both states. Qubit can be 0, 1 and any value in between at the same time, until an act of measurement is performed which forces it to relinquish all possible states except for one. Act of measurement turns the Qubit into a classical bit and all the Quantum mechanical advantage is lost. This is where property of Entanglement helps out. Quantum Entanglement is the phenomena under which properties of two particles that have previously interacted are inextricably linked in such a way that any change in the state of one particle simultaneously changes the state of other, and this holds true even if the two particles are at opposite ends of universe. Superposition of Qubit is maintained while figuring out its state by performing the measurement on its Entangled pair from which state of Qubit under consideration is inferred. Quantum Entangled bits have higher correlation than two classical correlated bits as established by Bell's inequality. While performing measurements through Entanglement, high correlation between the two Qubits is desirable for faithful results. Correlation giving a fidelity of 96-97% has been achieved by Professor Andrea Morello and his team.
Fact that Qubit can be in two state at same time allows for performing millions of iterations simultaneously making Quantum computers astonishingly superior than classical ones. Quantum computers use sequence of Qubits. A Qubit can be 0, 1 and all points in between at same time. Quantum computer with two Qubits can be in 4 different states at same time. Quantum computer with n Qubits can be in 2^n different states at the same time on the other hand a classical computer can only be in one of these 2^n states at any given time. Thus with every additional Qubit computing power grows exponentially. A Qubit has 2 key states denoted as 0=(1 0) and 1=(0 1) known as basis states. Quantum computer uses these states to perform iterations according to unitary matrix transformation. Theory and logic of Qubit computations is getting developed and numerous methods have been submitted to realize Quantum computing. One such method could be Quantum Annealing as indicated by T Lanting et al. Scientists so far have achieved successful multiplication of two integers using a Quantum computing method.
Quantum computers are based on behavior of matter at Quantum level. Manner in which the spin, energy or speed of these particles changes on interaction is used to create the logic based on which Quantum logic gates are created which are then used to operate on a set of Quantum inputs so called Qubits to yield an output. Qubits are Input to Quantum computers but output comes in form of classical bits because act of getting an output forces particles to relinquish all states they can be in except for one. Binary computer uses binary code as input which is then operated upon using logic circuits made of binary logic gates such as AND, OR, XOR. A binary logic gate is a realization of binary operators such as AND or NOT operator and are made using transistors such as a CMOS transistor. Architecture of Quantum computer is different from architecture of binary computers. In a Quantum computer, Quantum transistors made of controlled Qubits are used to create Quantum gates in order to realize basic Quantum logical operators as in unitary matrix which are then used to create Quantum logic circuits designed to solve real world problems. Code corresponding to such circuits is developed and used for programming. Quantum algorithm is used for creating codes for solving problems using Quantum computers. Based on the definition of Qubit, Quantum transistors have been created such as single atom transistor wherein by controlling the state of Qubit, conduction path can be opened or closed. Using single electron Qubit, Quantum logic gates have been created such as the CNOT gate, a two Qubit gatewherein target Qubit flips its spin when control Qubit is pointing down and maintains its spin when control Qubit is pointing up. Here spin of electron serves as Qubit and control is exercised through microwaves. This 2 Qubit gate alongwith single Qubit operations can be used to create any other gate set. It gives us a way of creating Quantum computers with 100s of Qubits. For sheer processing power, Quantum computer with 300 Qubits will have more computing ability than all binary computers on Earth combined. Quantum computer with 300 Qubits in Entanglement will have processing power equivalent to 2300 bit conventional computer. 2300 is about the number of particles in observable universe.
Vector representation is used to present Quantum states mathematically. Mathematically a Qubit can be presented in terms of its basis vector states as
2 Qubits in terms of their 4 basis vector states can be shown as
Quantum logic gate operation represents the multiplication between matrix representing it and vector representing Quantum state of Qubits. Quantum logic gate acting on k Qubits is represented as 2k x 2kunitary matrix. Qubits are input and output depends on type of Quantum logic gate used. With clear understanding of Quantum state mathematics, logic circuits can be designed to realize operations such as addition, multiplication, division, encoding, decoding, multiplexing et al and to form registers to store information on Qubits. Quantum transistors are used to construct Quantum logic gates. Quantum computer components such as processor, memory, I/O devices are created using Logic circuits made of Quantum logic gates. Communication protocols for allowing communication between the various components has been developed and is getting improved. Toffoli, Feynman, CNOT, Pauli X, Pauli Y, Pauli Z, Fredkin are some of the Quantum logic gates we have. Pauli X gate corresponds to rotation of Bloch sphere around X axis by π radian. It flips the state of input Qubit. Other gates have their own effects. We have the math and the logic, work is going on to figure out ways of realizing it to build working Quantum computers.
Models of Quantum computing include Adiabatic, one way, Quantum gate array and Topological. Many methods are available for implementing a Quantum computer such as Nuclear magnetic resonance, Fullerine based ESR, Linear optical, Trapped ion and Quantum dot. Logic of Quantum computing is far more complex than classical binary logic and requires simplification. Apart from this Scientists have to deal with Decoherence while designing these Quantum computers. Decoherence is the characteristic of getting into disorderly and unorganized state due to external interference or internal causes. Quantum state of Qubit changes with slightest of disturbance. To do calulations its essential to maintain their state that is up spin or down spin state for example, for entire duration of calculation. Scientists try to work around this problem by keeping Qubits in super cooled, ultra vacuum environment causing them to get in Quantum mechanical ground state. Liquid Nitrogen or liquid Helium is used for cooling. Preservation of Quantum state has been achieved for a maximum period of upto 2-3 hours so far. With more and more research in Quantum error correction, factors that can affect the state of Qubits are being recognized and ways of neutralizing those factors are getting created by research teams around the world. We only have a certain probability of getting the expected result when computing using quantum mechanical properties because state of particles at Quantum level cannot be measured with absolute certainty, we can only have a probability of one result or other determined according to Heisenberg uncertainty principle. This is why Quantum algorithms have to be run several times in succession to get result expected as per Quantum logical operators (unitary matrix transformations).
Researchers at the National Institute of Standards and Technology (NIST) have now managed a significant breakthrough by ‘teleporting’ or transferring, quantum information from one photon to another over a distance of 100 km of optical fiber. In this experiment as shown in their infographic they created a Photon and then split it in two using a special crystal generating a pair of entangled photons whose states are identical. One of the Entangled Photon is transported to receiving end through a spool of Optical Fiber. Then they generate the input Photon and select its state either early, late or a superposition of both. Input and helper Photon are made to meet at a beam splitter with a 50/50 chance of getting straight through or reflecting at an angle. Detectors developed at NIST and based on superconducting nanowires made of molybdenum silicide are placed suitably to detect the arrival of Photons. When one detector clicks early and the other late, it means Photons are out of phase. Detectors at receiving station measure the state of output Photons from which the state of input photon can be inferred. Thus teleportation of Quantum information is achieved. NIST’s Marty Stevens says “Only about 1 percent of photons make it all the way through 100 km of fiber”.
This is nothing like the general idea of Teleportation but it’s a great progress towards achieving the same. After all this is how the first conventional computers were developed and over 50 years of constant improvements have given us the computer and internet as we know it. Just remember the early experiments on Silicon and Germanium crystals in order to develop the very first transistors. We know that teleportation in principle is achievable because of the insight provided by the team of C.H. Bennett, G. Brassard, C. Crepeau, R. Jozsa, A. Peres, and W. Wootters. They pointed that complete teleportation of quantum information can be achieved in theory at least. Say you want to teleport object A. You can do this by scanning the quantum state of A and another object B together. The unscanned part is transferred to another object C through B which is Entangled with C. Using the scanned data of original Quantum state of object A, one of many treatments can be applied to C in order to recreate the complete original Quantum state of A, transforming C into A. This theory has been used by many scientists to demonstrate quantum teleportation at numerous occasions.
Anton Zeilinger and his team are carrying out Photon teleportation between the Islands of La Palma and Tenerife, over a distance of 143 km through open space. In their experiments they create two identical Photons (Heralded Single Photon), one of which is transported to Tenerife over a high energy Laser. A third Photon which they are going to teleport is brought close to the Photon at La Palma and their interactions are observed. Due to entanglement the state of distant Photon changes with the state of the Photon at the sending station. The observations made at sending station are used to convert the photon at Tenerife into an exact copy of the third Photon. A number of Photons have already been teleported using this method.
These experiments are very early steps towards making Quantum communication possible and creating Quantum Internet. Since a qubit cannot be copied, as any attempt to do so will alter the information due to uncertainty principle, information can be sent and received securely over Quantum Internet. Work is going on for the development of Quantum computer at institutes like MIT, IQC and corporations like IBM, Google. With Quantum Internet all the Quantum computers in world can be instantaneously connected and with help of Quantum Entanglement may be we could create a universal network one day, enabling us to communicate from anywhere in the universe instantaneously.
Nearly 1% mass of Protons and Neutrons is attributed to the mass of the three quarks that constitutes them and the remaining 99% is attributed to the strong nuclear force that binds these Quarks together. The Strong Nuclear Force is carried by a field of Gluons (virtual particles), which keeps fluctuating in and out of existence. The energy of these fluctuations is what renders the remaining mass of Protons and Neutrons and since together these Nucleons account for nearly all the mass of normal matter, it can be declared that close to 99% mass of normal matter keeps going in and out of existence. Equations of quantum chromodynamics, or QCD, describes the strong nuclear force. In most cases, these equations are too difficult to solve. Consequentially a new approach called Lattice QCD was developed which models smooth space and time as a grid of pixels. This allows for creation of close computer simulations of Strong Nuclear Force.
Virtual Gluons, Virtual Quarks and Anti Quarks are constituents of Quantum vacuum. Virtual Quark-Anti Quark pairs can appear suddenly and for an instant transform a proton into a more exotic particle. In fact, the proton as we know it is the combination of all these possibilities going at once. Virtual quarks make the calculations much more complicated, involving a matrix of more than 10,000 trillion numbers, says team member Stephan Dürr of the John von Neumann Institute for Computing in Jülich, Germany. A calculation involving that much data is beyond the capability of computers we have currently.
To calculate the mass of protons and neutrons using computer simulations, Dürr’s team used months of time on parallel computer network at Jülich. The network can handle 200 teraflops or 200 trillion arithmetical calculations per second. Dürr says- “We spent an enormous effort to make sure our code would make optimum use of the machine”. Without accounting for the Virtual Quarks, the simulations got proton mass wrong by about 10%, with them, Dürr gets a figure within 2% of the value measured by experiments.
Quark and Lepton are Fermions. So far we know of six Quarks named Up, Down, Charm, Strange, Top and Bottom, all having spin of 1/2. There is an anti particle pair for each one of them. They all carry fractional charge and they all have mass. Up Quark carries charge of +2/3 and Down Quark carries charge of -1/3. A Proton is two Up Quarks and a Down Quark held together by three Gluons. Since overall spin is half integer, Proton is a type of composite Fermion classified under the name of Baryon- particles made of three Quarks. Before 1987 it was thought that spin of Protons is a resultant of spin of its three constituent Quarks. But the 1987 European Muon Collaboration test indicated that this was not correct. It turned out that Quarks contribute only a very little, 25% at most to the overall spin of Protons. Scientists at RHIC have come up with conclusive evidence that contribution of Gluons to overall spin of Protons is almost same as that of Quarks, a value in the range of 20% to 30% of total Proton spin. Remaining spin might be coming from orbital angular momentum of Quark-Gluon system buzzing around confined by the weak force. Confinement might also be contributing to mass of Proton apart from the Higgs field contribution. Missing spin problem was named Proton spin Crisis. Neutron is another composite Fermion made of two Down Quarks and one Up Quark held together by three Gluons. Because it is made of three Quarks, Neutron also is a Baryon. Baryons are strongly interactive in nature. Protons can exist freely for extremely long time, free Neutrons on the other hand have a mean lifetime of 881.5±1.5 s. At the end of life, free Neutrons decay into Proton, Electron and Electron Antineutrino. Nucleus of a Carbon-13 atom is also a composite Fermion as it is formed by six Protons and seven Neutrons, making overall spin odd half integer. 
For Every particle in standard model an anti particle exists. Anti particles are same as particles except for their charge which is opposite. For example nucleus of antiatom is negatively charged but the Positrons whirling around are positively charged making the antiatom neutral. Particle and anti particle if brought together, annihilate each other converting into energy. If all matter in Universe is replaced with 
