Integrated Quantum Optics Lab

Large-scale integrated quantum photonic devices

Generating, controlling and detecting quantum states of light with large-scale quantum photonic circuits opens the way to realising quantum technologies for applications in quantum computing, simulation, sensing, machine learning and communication. Silicon photonics, a CMOS comparable and densely integrable platform, allows a monolithic integration of many spontaneous four-wave mixing single-photon sources, large-scale high-fidelity quantum circuits, and high-efficiency superconducting nanowire single-photon detectors. Silicon quantum photonics is becoming a scalable, programmable and robust platform for quantum science and technology. We developed a highly controllable multidimensional entanglement platform on a large-scale silicon-photonics quantum circuit able to generate, manipulate and measure entangled qudit states with high precision, controllability and universality, which integrates more than 550 photonic components, including 16 identical photon-pair sources and 93 programmable phase-shifters.

Quantum computing with photons

Photon is a pioneer physical system for analog quantum computing such as quantum Boson sampling and quantum random walk, and for universal linear-optical quantum computing based on the cluster-state model. The former is a promising candidate to demonstrate quantum supremacy, while the later recently has significant progresses towards large-scale quantum computing, such as the demonstrations of ten-photons and 18-qubits entangled-states by Prof. Pan's group in USTC. We are currently developing scalable Boson samplers and new on-chip schemes for the creation and control of largely entangled states for optical quantum computing. Remarkably, it is estimated by Prof. Rudolph from Imperial Collage London that today's silicon photonics manufacture abilities allow the creation of tens of thousands of photons entangled in a state universal for quantum computation.

Quantum simulation of complex quantum systems

Quantum simulation is to simulate and predict complex quantum systems behaviours on a controllable quantum machine or quantum computer, in which the physical systems are approximated by simplified models and the models are simulated by the machines. Through measuring the consistency of the model predictions from the simulator with the real experimental data and estimating their quantum likelihoods, it can efficiently simulate and characterize the underpinning Hamiltonian models and verifying the predictions, with the use of classical machine learning. Quantum simulator, as a specific quantum computer, could in future provide a powerful tool to compute molecular energies and simulate molecular dynamics, a task impossible for classical computers. We recently developed a new algorithm is capable of finding the ground-state and excited-states in a way that seems to have no direct analogue on a classical computer, providing a new way of studying physics and chemistry.

Chip-based quantum communication network

A future chip-based quantum communication network requires coherent entanglement generation, transmission, distribution and manipulation as well as the teleportation of quantum states, in which entangled photons are flying amongst a complex network of many separate on-chip subsystems. A coherent conversion of photon's different degrees of freedom such as path, time bin, polarisation and orbital angular moment mode, can be exploited for the preservation of high-quality quantum entanglement within a single system throughout the whole quantum processes. We are developing high-performance quantum communications technologies and systems with the use of silicon-based quantum photonic chips, which is manufacturing low-cost and comparable with the telecommunication infrastructure and CMOS electronics. A further integration of stationary qubits in matter with an efficient interaction of flying qubits is essential for quantum information storage and quantum network.

Test quantum mechanical foundation

Since the birth of quantum mechanics in 1930s, photon has been playing a key role in the study and understanding of quantum theory, such as non-locality and wave-particle duality. I am interested in exploiting the beauties of photons, such as superposition and entanglement, to study the foundation of quantum physics. Photons allow us to create, control and analyze multidimensional entanglement, which entangles pairs of photon each has 15 states, observe high-quality quantum correlations, such as generalized Bell violations and Einstein-Podolsky-Rosen steering violations, and implement multidimensional quantum protocols such as self-testing entangled states, multidimensional quantum randomness expansion, high key-rates and noise-resilience QKD.,