Mapping and measuring large-scale photonic correlation with single-photon imaging

Abstract

Quantum correlation and its measurement are essential in exploring fundamental quantum physics problems and developing quantum enhanced technologies. Quantum correlation may be generated and manipulated in different spaces, which demands different measurement approaches corresponding to position, time, frequency and polarization of quantum particles. In addition, after early proof-of-principle demonstrations, it is of great demand to measure quantum correlation in a Hilbert space large enough for real quantum applications. When the number of modes goes up to several hundreds, it becomes economically unfeasible for single-mode addressing and also extremely challenging for processing correlation events with hardware. Here we present a general and large-scale measurement approach of Correlation on Spatially-mapped Photon-Level Image (COSPLI). The quantum correlations in other spaces are mapped into the position space and are captured by single-photon-sensitive imaging system. Synthetic methods are developed to suppress noises so that single-photon registrations can be faithfully identified in images. We eventually succeed in retrieving all the correlations with big-data technique from tens of millions of images. We demonstrate our COSPLI by measuring the joint spectrum of parametric down-conversion photons. Our approach provides an elegant way to observe the evolution results of large-scale quantum systems, representing an innovative and powerful tool added into the platform for boosting quantum information processing.Quantum correlation, as one of the unique features of quantum theory, plays a crucial role in quantum information applications. After experiencing quantum evolutions, e.g. quantum interference, quantum particles can be correlated in more diverse ways than the classical counterpart. For example, Hong-Ou-Mandel (HOM) interference can reveal the nonclassical bunching properties of photons [1]. These correlation characteristics are crucial in quantum computing [2][3][4][5], quantum simulation[6-9] and quantum communication [10][11][12][13].In theory, especially in the field of quantum computing, if we manage to send enough entangled photons into plenty of modes and operate their superposition states simultaneously, we would be able to obtain sufficiently large quantum state space that may enable a higher computational power than classical computers. In practice, it may still be acceptable to place single photon detector behind each spatial mode for comparably small systems [9, 14-16]. However, it will become both technically challenging and economically unfeasible to address thousands of modes simultaneously with single photon detectors, and therefore become a decisive bottleneck preventing from detecting state spaces large enough for real quantum applications.Thankfully, recent advances of charge-coupled device (CCD) cameras make it possible to directly image spatial output results at a single-photon level [17][18][19][20][21][22][23][24]. HOM interference was also successfully verified by low-noise corre...

Simulating quantum many-body dynamics on a current digital quantum computer

“…These quantum devices can be implemented in a large number of ways, for example, using ultracold trapped ions [6][7][8][9][10][11], cavity quantum electrodynamics (QED) [12][13][14][15], photonic circuits [16][17][18], silicon quantum dots [19][20][21], and theoretically even by braiding, as yet unobserved, exotic collective excitations called non-abelian anyons [22][23][24]. One of the most promising approaches is using superconducting circuits [25][26][27], where recent advances have resulted in devices consisting of up to 72 qubits, pushing us ever closer to realising so-called quantum supremacy [28].…”

Experimental Collision-Free Dominant Boson Sampling

“…The main reason of this deviation from the theoretical prediction is that the second transforming zone after the interference section introduces differential losses for different channels, which further influences the out-coming results. This shortcoming can be overcome in the future by adopting the imaging-based large scale correlation measurement [27] since we could directly measure the 2D cross section structure.…”

“…These results shows the capability of 3D structure and femtosecond laser writing technique. Such features combining on-chip photon generation [26] and imaging based large scale quantum correlation measurement [27] could open up a new regime for boson sampling.…”

Fast imaging of multimode transverse-spectral correlations for twin photons

“…Single-photon-resolving cameras on the other hand naturally offer spatial or angular resolution, which can be exploited in super-resolved imaging [28][29][30][31][32], interferometry [33], characterization [34,35] or, similarly as in the previous case, observation of quantum interference effects such as in the Hong-Ou-Mandel-type experiments [36]. Recently however, the capability of cameras has been expanded by invoking a well-known mode conversion technique, in which Sun et al simply observed spectral correlation with the help of a diffraction grating [37]. It is thus a promising approach to use a camera to observe many DoFs simultaneously.…”