From Multiphoton Interference To Boson Sampling Experiments

The main contents of this thesis are the experimental study of several problems based on multiphoton interference.Multiphoton interference is a pure quantum effect with wide applications including fundamental tests of quantum mechanics,quantum precision measurement,quantum computation and quantum simulation.In fundamental tests of quantum mechanics,the GHZ theorem disproves directly the concept of EPR elements of reality in an all-versus-nothing way.A three-qubit experimental demonstration of the GHZ theorem was achieved in 2000,followed by demonstrations for more qubits.Still,the GHZ theorems underlying the tests can be reduced to a three-qubit one.By closing this loophole,we show an irreducible four-qubit GHZ theorem,and report its experimental demonstration.In quantum precision measurements,it has been found that multiphoton entan-gled states can be used to beat the shot-noise limit of classical measurement techniques.However,the preparation and detection of multiphoton entangled states usually depend on post-selection techniques or inefficient nonlinearity.This greatly reduce the power of multiphoton entanglement in quantum precision measurement.Through using both path and polarization modes,we develop a general technique that simplifies the con-struction of quantum Fourier transform interferometers.On this basis,we observed the superresolution of up to four photons deterministically.In quantum computation and quantum simulation,boson-sampling is anew hotspot of multiphoton interference related research,and it is one of the most promising mod-els to show quantum supremacy over classical computers in the near term.We ex-perimentally studied the boson-sampling based on two different single-photon sources:probabilistic single-photon sources based on parametric down-conversion,and deter-ministic quantum-dot single-photon sources.The former can overcome the exponential decay problem of multiphoton brightness by increasing the number of single-photon sources and randomizing the inputs,but the experimental implementation of scattershot boson-sampling is still limited by the low photon collection efficiency and the noise from multipair emission.We systematically studied this problem and proposed solu-tion.The latter does not suffer from multipair noise problem in principle.Recently,our group has developed a quantum-dot single-photon source with simultaneously high efficiency,purity and indistinguishabilty.On that basis,we set up a time-bin-encoding programmable boson-sampling experimental platform.For the first time,the number of photons is improved to four in a boson-sampling experiment,laying a solid foundation for the goal of quantum supremacy.