All photons are equal but some photons are more equal than others

Töppel, Falk; Aiello, Andrea; Leuchs, Gerd

doi:10.1088/1367-2630/14/9/093051

Cited by 10 publications

(9 citation statements)

References 32 publications

(41 reference statements)

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“…In the experiment, particles are typically not perfectly identical, but they carry degrees of freedom by which they can be distinguished to a certain extent [50]. Distinguishability is described in the most general fashion by pooling all possibly distinguishing degrees of freedom of the particles in the jth input mode into an "internal" state |Φ j (particles in the same spatial mode are fully indistinguishable, which is fulfilled well in experiments with photons).…”

Section: A Scattering Scenariomentioning

confidence: 99%

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Sampling of partially distinguishable bosons and the relation to the multidimensional permanent

2015

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The collective interference of partially distinguishable bosons in multi-mode networks is studied via double-sided Feynman diagrams. The probability for many-body scattering events becomes a multi-dimensional tensor-permanent, which interpolates between distinguishable particles and identical bosons, and easily extends to mixed initial states. The permanent of the distinguishability matrix, composed of all mutual scalar products of the single-particle mode-functions, emerges as a natural measure for the degree of interference: It yields a bound on the difference between event probabilities for partially distinguishable bosons and the idealized species, and exactly quantifies the degree of bosonic bunching.

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Section: A Scattering Scenariomentioning

confidence: 99%

“…Physically, Eqs. (50)(51)(52) quantify the impact of interference contributions on the probability of individual events, i.e. perm(S) quantifies the strength of bosonic exchange contributions in Eq.…”

Section: B Bounds On the Deviation From The Idealized Casesmentioning

confidence: 99%

Sampling of partially distinguishable bosons and the relation to the multidimensional permanent

2015

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“…In Eqs. (45) or (46) the squared absolute value is taken of a coherent sum of the matrix permanents. In case of single photons from independent sources, i.e., when the input density matrix is given by Eq.…”

Section: Output Probability In Terms Of the Matrix Permanentsmentioning

confidence: 99%

“…[36]) where it was found that a single parameter is both a degree of indistinguishability and a degree of quantum coherence (how the degree of indistinguishability depends on different parameters in spectral states of photons is recently studied in Ref. [45]).…”

Section: Mandel's Degree Of Indistinguishability For Two Photonsmentioning

confidence: 99%

Partial indistinguishability theory for multiphoton experiments in multiport devices

2015

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We generalize an approach for description of multi-photon experiments with multi-port unitary linear optical devices, started in Phys. Rev. A 89, 022333 (2014) with single photons in mixed spectral states, to arbitrary (multi-photon) input and arbitrary photon detectors. We show that output probabilities are always given in terms of the matrix permanents of the Hadamard product of a matrix built from the network matrix and matrices built from spectral state of photons and spectral sensitivities of detectors. Moreover, in case of input with up to one photon per mode, the output probabilities are given by a sum (or integral) with each term being the absolute value squared of such a matrix permanent. We conjecture that, for an arbitrary multi-photon input, zero output probability of an output configuration is always the result of an exact cancellation of quantum transition amplitudes of completely indistinguishable photons (a subset of all input photons) and, moreover, is independent of coherence between only partially indistinguishable photons. The conjecture is supported by examples. Furthermore, we propose a measure of partial indistinguishability of photons which generalizes Mandel's observation, and find the law of degradation of quantum coherence in a realistic Boson-Sampling device with increase of the total number of photons and/or their "classicality parameter".

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“…However, the BS process should fulfill several conditions for its computational hardness: low photon density (M ≫ N ), complete photon indistinguishability, and randomness of unitary operations. Most of all, the complete photon indistinguishability condition is hard to meet since photons usually carry some internal degrees of freedom that makes them partially distinguishable in experimental realizations [2]. There have been many quantitative approaches to analyze the multiphoton interference phenomena of partial distinguishable photons in LON [3][4][5][6][7][8][9][10][11], in which the distinguishability matrix is introduced to evaluate the mutual distinguishability of each particle to others.…”

Section: Introductionmentioning

confidence: 99%

Partial distinguishability as a coherence resource in boson sampling

Chin

Huh

2019

Quantum Inf Process

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Quantum coherence is a useful resource which is consumed to accomplish several tasks that classical devices are hard to fulfill. Especially, it is considered to be the origin of quantum speedup for many computational algorithms. In this work, we interpret the computational complexity of the linear optical network with partially distinguishable photons from the perspective of coherence resource theory. With incoherent operations that preserve the diagonal elements of quantum states up to permutation, which we name permuted genuinely incoherent operation (pGIO), we present some evidence that the decrease of coherence corresponds to a computationally less complex system of partially distinguishable boson sampling.

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All photons are equal but some photons are more equal than others

Cited by 10 publications

References 32 publications

Sampling of partially distinguishable bosons and the relation to the multidimensional permanent

Sampling of partially distinguishable bosons and the relation to the multidimensional permanent

Partial indistinguishability theory for multiphoton experiments in multiport devices

Partial distinguishability as a coherence resource in boson sampling

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