Two-photon interference between disparate sources for quantum networking (original) (raw)

Quantum networks involve entanglement sharing between multiple users. Ideally, any two users would be able to connect regardless of the type of photon source they employ, provided they fulfill the requirements for two-photon interference. From a theoretical perspective, photons coming from different origins can interfere with a perfect visibility, provided they are made indistinguishable in all degrees of freedom. Previous experimental demonstrations of such a scenario have been limited to photon wavelengths below 900 nm, unsuitable for long distance communication, and suffered from low interference visibility. We report two-photon interference using two disparate heralded single photon sources, which involve different nonlinear effects, operating in the telecom wavelength range. The measured visibility of the two-photon interference is 80 6 4%, which paves the way to hybrid universal quantum networks.

High-visibility two-photon interference at a telecom wavelength using picosecond-regime separated sources

Physical Review A, 2010

We report on a two-photon interference experiment in a quantum relay configuration for long distance quantum communication at a telecom wavelength. In contrast to already reported regimes, namely femtosecond and CW, we propose for the first time to employ the picosecond regime which allows achieving a near-perfect visibility two-photon interference using only standard telecom components and detectors. Our experiment is based on two photons at 1550 nm emitted by two separate PPLN waveguides. We show a net interference visibility of 99% which clearly proves the very high potential of our experimental scheme to achieve quantum networking applications in real conditions.

Generalized multi-photon quantum interference

2015

Non-classical interference of photons lies at the heart of optical quantum information processing. This effect is exploited in universal quantum gates as well as in purpose-built quantum computers that solve the BosonSampling problem. Although non-classical interference is often associated with perfectly indistinguishable photons this only represents the degenerate case, hard to achieve under realistic experimental conditions. Here we exploit tunable distinguishability to reveal the full spectrum of multi-photon non-classical interference. This we investigate in theory and experiment by controlling the delay times of three photons injected into an integrated interferometric network. We derive the entire coincidence landscape and identify transition matrix immanants as ideally suited functions to describe the generalized case of input photons with arbitrary distinguishability. We introduce a compact description by utilizing a natural basis which decouples the input state from the int...

Experimental Two‐Way Communication with One Photon

Advanced Quantum Technologies, 2019

Superposition of two or more states is one of the fundamental concepts of quantum mechanics and provides the basis for several advantages offered by quantum information processing. In this work, we experimentally demonstrate that quantum superposition allows for two-way communication between two distant parties that can exchange only one particle once, an impossible task in classical physics. This is achieved by preparing a single photon in a coherent superposition of the two parties' locations. Furthermore, we show that this concept allows the parties to perform secure and anonymous quantum communication employing one particle per transmitted bit. These important features can lead to the realization of new quantum communication schemes, which are simultaneously anonymous, secure and resource-efficient.

Reliable and efficient control of two-photon interference in the frequency domain

2011

Frequency-entangled photons can be readily produced using parametric down-conversion. We have recently shown how such entanglement could be manipulated and measured using electro-optic phase modulators and narrow-band frequency filters, thereby leading to two-photon interference patterns in the frequency domain. Here we introduce new theoretical and experimental developments showing that this method is potentially a competitive platform for the realization of quantum communication protocols in standard telecommunication fibres. We derive a simple theoretical expression for the coincidence probabilities and use it to optimize a Bell inequality. Furthermore, we establish an equivalence between the entangledphoton scheme and a classical interference scheme. Our measurements of two-photon interference in the frequency domain yield raw visibilities in excess of 99%. We use our high quality setup to experimentally validate the theoretical predictions, and in particular we report a violation of the CH74 inequality by more than 18 standard deviations.

Generalized quantum interference of correlated photon pairs

Scientific reports, 2015

Superposition and indistinguishablility between probability amplitudes have played an essential role in observing quantum interference effects of correlated photons. The Hong-Ou-Mandel interference and interferences of the path-entangled photon number state are of special interest in the field of quantum information technologies. However, a fully generalized two-photon quantum interferometric scheme accounting for the Hong-Ou-Mandel scheme and path-entangled photon number states has not yet been proposed. Here we report the experimental demonstrations of the generalized two-photon interferometry with both the interferometric properties of the Hong-Ou-Mandel effect and the fully unfolded version of the path-entangled photon number state using photon-pair sources, which are independently generated by spontaneous parametric down-conversion. Our experimental scheme explains two-photon interference fringes revealing single- and two-photon coherence properties in a single interferometer s...

Experimental quantum teleportation and multiphoton entanglement via interfering narrowband photon sources

Physical Review A, 2009

In this letter, we report a realization of synchronization-free quantum teleportation and narrowband three-photon entanglement through interfering narrowband photon sources. Since both the single-photon and the entangled photon pair utilized are completely autonomous, it removes the requirement of high demanding synchronization technique in long-distance quantum communication with pulsed spontaneous parametric down-conversion sources. The frequency linewidth of the three-photon entanglement realized is on the order of several MHz, which matches the requirement of atomic ensemble based quantum memories. Such a narrowband multi-photon source will have applications in some advanced quantum communication protocols and linear optical quantum computation.

Analysis of photon-mediated entanglement between distinguishable matter qubits

We theoretically evaluate establishing remote entanglement between distinguishable matter qubits through interference and detection of two emitted photons. The fidelity of the entanglement operation is analyzed as a function of the temporal-and frequency-mode matching between the photons emitted from each quantum memory. With a general analysis, we define limits on the absolute magnitudes of temporal-and frequency-mode mismatches in order to maintain entanglement fidelities greater than 99% with two-photon detection efficiencies greater than 90%. We apply our analysis to several selected systems of quantum memories. Results indicate that high fidelities may be achieved in each system using current experimental techniques, while maintaining acceptable rates of entanglement. Thus, it might be possible to use two-photon-mediated entanglement operations between distinguishable quantum memories to establish a network for quantum communication and distributed quantum computation.

Long-distance quantum communication through any number of entanglement-swapping operations

Physical Review A, 2014

We develop a theory and accompanying mathematical model for quantum communication via any number of intermediate entanglement swapping operations and solve numerically for up to three intermediate entanglement swapping operations. Our model yields two-photon interference visibilities post-selected on photon counts at the intermediate entanglement-swapping stations. Realistic experimental conditions are accommodated through the parametric down-conversion rate, photon-counter efficiencies and dark-count rates, and instrument and transmission losses. We calculate achievable quantum communication distances such that two-photon interference visibility exceeds the Bell-inequality threshold.

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