General Rules for Bosonic Bunching in Multimode Interferometers

2008

We propose an experiment to directly prove the commutation relation between bosonic annihilation and creation operators, based on the recent experimental success in single-photon subtraction and addition. We devise a single-photon interferometer to realize coherent superpositions of two sequences of photon addition and subtraction. Depending on the interference outcome, the commutation relation is directly proven or a highly nonclassical state is produced. Experimental imperfections are assessed to show that the realization of the scheme is highly feasible.

Physical Review Letters, 1996

A two-photon detection scheme is used to measure three-and four-photon correlations in a light beam and study their time dependence. PACS numbers: 42.65.Ky, 42.50.Ar Photon correlations of light beams are intimately connected to source dynamics. They are characteristic of sources that produce them [1]. Thus while photons from thermal sources exhibit bunching [2], those from nonthermal sources may exhibit antibunching . Photon correlations are usually discussed in terms of the second order intensity correlation function ͗I͑t͒I͑t 1 t͒͘, where I͑t͒ is the intensity of light beam and angular brackets indicate averaging with respect to the state of the field. The second order correlation function is proportional to the probability of detecting two photons separated by an interval t. It is clear that even for uncorrelated photons there is some finite probability, proportional to ͗I͑t͒͘ ͗I͑t 1 t͒͘ ͗I͘ 2 , of detecting a pair of photons separated by an interval t. A measure of intrinsic two-photon bunching is therefore provided by the correlation function k 2 ͑t͒ ͗DI͑t͒DI͑t 1 t͒͗͘͞I͘ 2 , where DI͑t͒ I͑t͒ 2 ͗I͘ represents deviations of light intensity from the mean. Here and in what follows we assume statistically stationary light beams. Similar to k 2 ͑t͒, we can introduce higher order correlation functions of light.

Optics Express, 2020

Particle identity and entanglement are two fundamental quantum properties that work as major resources for various quantum information tasks. However, it is still a challenging problem to understand the correlation of the two properties in the same system. While recent theoretical studies have shown that the spatial overlap between identical particles is necessary for nontrivial entanglement, the exact role of particle indistinguishability in the entanglement of identical particles has never been analyzed quantitatively before. Here, we theoretically and experimentally investigate the behavior of entanglement between two bosons as spatial overlap and indistinguishability simultaneously vary. The theoretical computation of entanglement for generic two bosons with pseudospins is verified experimentally in a photonic system. Our results show that the amount of entanglement is a monotonically increasing function of both quantities. We expect that our work provides an insight into deciph...

2014

A boson sampling device is a specialised quantum computer that solves a problem which is strongly believed to be computationally hard for classical computers . Recently a number of small-scale implementations have been reported , all based on multi-photon interference in multimode interferometers. In the hardto-simulate regime, even validating the device's functioning may pose a problem . In a recent paper, Gogolin et al. [7] showed that so-called symmetric algorithms would be unable to distinguish the experimental distribution from the trivial, uniform distribution. Here we report new boson sampling experiments on larger photonic chips, and analyse the data using a scalable statistical test recently proposed by Aaronson and Arkhipov . We show the test successfully validates small experimental data samples against the hypothesis that they are uniformly distributed. We also show how to discriminate data arising from either indistinguishable or distinguishable photons. Our results pave the way towards larger boson sampling experiments whose functioning, despite being non-trivial to simulate, can be certified against alternative hypotheses.

Canadian Journal of Physics, 2008

We first devise a scheme to perform a universal entangling gate via controlled collisions between pairs of atomic qubits trapped with optical tweezers. Second, we present a modification to this scheme to allow for the preparation of atomic Bell pairs via selective excitation, suitable for quantum-information-processing applications that do not require universality. Both these schemes are enabled by the inherent symmetries of identical composite particles, as originally proposed by Hayes et al. Our scheme provides a technique for producing weighted graph states, entangled resources for quantum communication, and a promising approach to performing a “loophole free” Bell test in a single laboratory.PACS Nos.: 03.65.Ud, 03.67.Mn, 32.80.Pj, 42.50.Vk

2013

The boson sampler proposed by Aaronson and Arkhipov is a non-universal quantum computer, which can serve as evidence against the extended Church-Turing thesis. It samples the probability distribution at the output of linear unitary optical network, with indistinguishable single photons at the input. Four experimental groups have already tested their small-scale prototypes with up to four photons. The boson sampler with few dozens of single photons is believed to be hard to simulate on a classical computer. For scalability of a realistic boson sampler with current technology it is necessary to know the effect of the photon mode mismatch on its operation. Here a nondeterministic model of the boson sampler is analyzed, which employs partially indistinguishable single photons emitted by identical sources. A sufficient condition on the average mutual fidelity 〈F〉 of the single photons is found, which guarantees that the realistic boson sampler outperforms the classical computer. Moreover...

International Journal of Quantum Information, 2020

Experimental demonstration of the quantum advantage over classical simulations with Boson Sampling is currently under intensive investigation. There seems to be a scalability issue to the necessary number of bosons on the linear optical platforms and the experiments, such as the recent Boson Sampling with 20 photons on 60-port interferometer by H. Wang et al., Phys. Rev. Lett.123 (2019) 250503, are usually carried out on a small interferometer, much smaller than the size necessary for the no-collision regime. Before demonstration of quantum advantage, it is urgent to estimate exactly how the classical computations necessary for sampling from the output distribution of Boson Sampling are reduced when a smaller-size interferometer is used. This work supplies such a result, valid with arbitrarily close to 1 probability, which reduces in the no-collision regime to the previous estimate by Clifford and Clifford. One of the results with immediate application to current experiments with Bo...

Physical Review A, 2016

Multi-photon interference results in modulations of output probabilities with phase shift periods that are much shorter than 2π. Here, we investigate the physics behind these statistical patterns in the case of well-defined photon numbers in the input and output modes of a two-path interferometer. We show that the periodicity of the multi-photon interference is related to the weak value of the unobserved intensity difference between the two arms of the interferometer. This means that the operator relations between the photon number differences in input, path, and output can be used to determine the periodicity of the experimentally observed quantum interference, establishing an important link between the classical causality of random phase interference and quantum effects that depend on the superposition of classically distinct possibilities.

The composite character of two-fermion bosons manifests itself in the interference of many composites as a deviation from the ideal bosonic behavior. A state of many composite bosons can be represented as a superposition of different numbers of perfect bosons and fermions, which allows us to provide the full Hong–Ou–Mandel-like counting statistics of interfering composites. Our theory quantitatively relates the deviation from the ideal bosonic interference pattern to the entanglement of the fermions within a single composite boson.

2012