@ Nanjing university, Nanjing
Quantum Photonics Lab, Nanjing University (QPL@NJU) focus on the generation, manipulation and detection of non-classical light, and their applications in fundamental tests of quantum physics and quantum information, especially in quantum tomography, quantum metrology and quantum simulation.
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Metrology is an essential technology to extract information of unknown parameters existing in the systems. The improvement of measurement accuracy can not only verify the existing physical theories, but also promote the development of new theories and technologies. In general, quantum metrology consists in four processes: the preparation of a probe, the dynamic process of its coupling with unknown parameters, the measurement of systems, and the estimation of parameters according to the measurement results. Due to the limitations of the physical properties, such as shot noise and uncertainty principle, the accuracy that can be achieved by classical measurement is the shot noise limit. Our interests lie in uncovering the fundamental limits of estimating parameters restricted by the laws of quantum mechanics. To improve the precision of parameter estimation, we invent and analyze many new methods such as weak value amplification, Bayesian feedback control, and SU(1,1) interferometer theoretically and experimentally. We are also interested in multi-parameter estimation and dynamic parameter estimation.
Quantum information technology is the core driving force for the revolutionary change of information technology and information industry in the future. Quantum resources play an important role in quantum information technology, such as entanglement, coherence, contextuality and EPR steering. With the development of quantum technologies, the requirement for both entanglement dimensionality and photon number increases, demanding largescale, controllable, and stable quantum photonic sources. In addition, one of the challenges in quantum technologies, especially in large scale quantum information networks, is preserving the fragile quantum resource in the presence of losses and noise. We focus on the preparation and regulation of highly integrated and extremely high dimensional quantum light sources by integrating a metalens array with a nonlinear crystal. We reveal the geometry of multidimensional quantum systems and infer the non-classical properties of quantum systems. In addition, we quantify experimentally the ability of a typical quantum optical detector, the weak-field homodyne detector, to detect coherence. We also study how the quantum resource can be distilled with effffective means, such as the distillation of Gaussian quantum resource (Entanglement, coherence, EPR steering) in lossy and noisy environment using noiseless linear amplifification (NLA).
Quantum computing, driven by principles of quantum mechanics, has been found to provide unprecedented speed-ups in solving classically intractable computational tasks. As building universal, fault-tolerant quantum computers is still a challenging task, restricted non-universal models have been developed to demonstrate the power of quantum computation and heralds the noisy intermediate-scale quantum (NISQ) era. Photonics has been a natural platform for quantum computation and quantum simulation, especially for quantum algorithms involving high-dimensional encoding and linear operations. In this line, we focus on the realization of novel quantum algorithms suitable for photonic technologies and the demonstration of intriguing properties of quantum systems. Recently, we exploit the advantages of photonics to realize a new regime of quantum algorithm — the quantum verification machine of nondeterministic polynomial time (NP) problems. Investigations on this topic, combining quantum computational complexity theory and photonic quantum technologies, are expected to extend the capability of NISQ devices.