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arXiv:2104.15014 · Physical Review A

Emulation of quantum measurements with mixtures of coherent states

Alexander B. Mikhalychev, Yong Siah Teo, Hyunseok Jeong, André Stefanov, Dmitri S. Mogilevtsev

Published May 13, 2022• 5 citations
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Abstract

We propose a methodology to emulate quantum phenomena arising from any nonclassical quantum state using only a finite set of mixtures of coherent states. This allows us to successfully reproduce well-known quantum effects using resources that can be much more feasibly generated in the laboratory. We present a simple procedure to experimentally carry out quantum-state emulation with coherent states, illustrate it emulating multiphoton NOON states with few phase-averaged coherent states, and demonstrate its capabilities in observing fundamental quantum mechanical effects, such as the Hong-Ou-Mandel effect, violating Bell inequalities and witnessing quantum nonclassicality.

DOI
10.1103/physreva.105.052206

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We propose a methodology to emulate quantum phenomena arising from any nonclassical quantum state using only a finite set of mixtures of coherent states. This allows us to successfully reproduce well-known quantum effects using resources that can be much more feasibly generated in the laboratory. We present a simple procedure to experimentally carry out quantum-state emulation with coherent states, illustrate it emulating multiphoton NOON states with few phase-averaged coherent states, and demonstrate its capabilities in observing fundamental quantum mechanical effects, such as the Hong-Ou-Mandel effect, violating Bell inequalities and witnessing quantum nonclassicality.
We propose a classical emulation methodology to emulate quantum phenomena arising from any non-classical quantum state using only a finite set of coherent states or their statistical mixtures. This allows us to successfully reproduce well-known quantum effects using resources that can be much more feasibly generated in the laboratory. We present a simple procedure to experimentally carry out quantum-state emulation with coherent states that also applies to any general set of classical states that are easier to generate, and demonstrate its capabilities in observing the Hong-Ou-Mandel effect, violating Bell inequalities and witnessing quantum non-classicality.
We propose a classical emulation methodology to emulate quantum phenomena arising from any non-classical quantum state using only a finite set of coherent states or their statistical mixtures. This allows us to successfully reproduce well-known quantum effects using resources that can be much more feasibly generated in the laboratory. Our results shed new light on an alternative operational meaning to non-classicality. We present a simple procedure to experimentally carry out quantum-state emulation with coherent states that also applies to any general set of classical states that are easier to generate, and demonstrate its capabilities in observing the Hong-Ou-Mandel effect, violating Bell inequalities and witnessing quantum non-classicality.
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ABSTRACT We report an experimental demonstration of room‐temperature Hong–Ou–Mandel (HOM) interference at a radio‐wave frequency of 120 MHz using single‐photon states built from phase‐averaged coherent states by the emulation procedure proposed in the recent work. This emulation approach enables observation of quantum effects in spectral regimes where conventional single‐photon sources and detectors are unavailable or require cryogenic conditions. By constructing a high‐fidelity approximation of a single‐photon state with phase‐averaged coherent states, we observe the normalized second‐order intensity correlation dips significantly below the classical limit of 0.5. The method allows for tunable noise suppression via optimization of the state representation. Our results establish the feasibility of using conditionally prepared classical states to simulate quantum interference phenomena in the radio‐frequency domain.
Understanding the causal influences that hold among the parts of a system is critical both to explaining that system’s natural behaviour and to controlling it through targeted interventions. In a quantum world, understanding causal relations is equally important, but the set of possibilities is far richer. The two basic ways in which a pair of time-ordered quantum systems may be causally related are by a cause-effect mechanism or by a common cause acting on both. Here, we show that it is possible to have a coherent mixture of these two possibilities. We realize such a nonclassical causal relation in a quantum optics experiment and derive a set of criteria for witnessing the coherence based on a quantum version of Berkson’s paradox.
We report an experimental demonstration of room-temperature Hong-Ou-Mandel (HOM) interference at a radio-wave frequency of 120 MHz using conditional build-up of quantum states from classical phase-averaged coherent states. This approach enables observation of quantum effects in spectral regimes where conventional single-photon sources and detectors are unavailable or require cryogenic conditions. By constructing a high-fidelity approximation of a single-photon state with phase-averaged coherent states, we observe the normalized second-order intensity correlation dips significantly below the classical limit of 0.5. The method allows for tunable noise suppression via optimization of the state representation. Our results establish the feasibility of using conditionally prepared classical states to simulate quantum interference phenomena in the radio-frequency domain. This technique opens the door to realizing other quantum protocols, such as Bell inequality tests, in frequency ranges where standard quantum technologies are currently infeasible.