Photonic Quantum Advantage

Quantum information is one of the most frontier research fields in recent years,which integrates many branches such as quantum physics,mathematics,computer science and materials science et al.Quantum technology has great advantage over classical ways on information transmission capacity,information security,and computational capability,owning to its special ways on information coding,storage,transmission,and manipulation ruled by quantum physics.Especially,the main aim of quantum computing is to achieve high-precision multi-qubit coherent manipulation on a large-scale scalable physical system.Among many candidates,photonic quantum computing plays an irreplaceable role due to some unique inherent advantages:resistance to decoherence at room temperature,high-precision qubit manipulation,and flying qubit which naturally interfaces for distributed quantum computation.In this paper,we will focus on photonic quantum computing,especially,the boson sampling task to realize quantum supremacy(or advantage).After many efforts,we finally realized quantum supremacy successfully.The works in this thesis include:1.We successfully realize long streams of 1000 near transform-limited single photons with mutual indistinguishability above 92%,which pave the way for large-scale photonic quantum technologies,also one of the prerequisites for boson sampling based on quantum-dot single-photon source;2.For the first time,we demonstrate a background-free method for the coherent excitation and control of a two-level quantum system using a phase-locked dichromatic electromagnetic field with no spectral overlap with the optical transition;3.For the first time,we address the 50%photon loss issue by coupling a single quantum dot with elliptical microcavities.The final polarized single-photon extraction efficiency is as high as 60%,which is impossible for all previous experiments;4.We demonstrate intensity squeezing of 0.59 dB in resonance fluorescence from a solid-state two-level system,which fills up the last piece of fundamental aspects of resonance fluorescence;5.For the first time,we realize an on-demand semiconductor source of entangled photons which simultaneously has high fidelity,efficiency and indistinguishability,from our new designed broadband bullseye microcavity;6.For the first time,we realize 5-photon boson sampling by using actively demultiplexed single-photon sources based on a quantum dot-micropillar and robust optical interferometers with 99%transmission efficiency,which beat early classical computers such as ENIAC and TRADIC;7.For the first time,we report robust lossy boson sampling which significantly increase sampling rate;8.For the first time,we demonstrate boson sampling with 20 input photons and a 60-mode interferometer in a 1014 Hilbert space,which enter a new realm of increasing size and complexity for photonic quantum computing with,a major step toward quantum supremacy.9.For the first time,we demonstrate quantum supremacy via photonic Gaussian boson sampling with 25 two-mode squeezed sources and a 100×100 ultralow loss linear optical network.The average photon number is 43.6,the largest detected photon number of 76,showing a quantum advantage of 1014 compared with the supercomputer Sunway Taihulight.