Single pairs of time-bin-entangled photons

Versteegh, Marijn A. M.; Reimer, Michael E.; Berg, A. van den; Juška, Gediminas; Dimastrodonato, V.; Gocalinska, Agnieszka; Pelucchi, E.; Zwiller, Val

doi:10.1103/physreva.92.033802

Cited by 32 publications

(18 citation statements)

References 53 publications

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“…Beside the near-optimal level of entanglement and indistinguishability of the emitted photons, our QDs emit in the spectral range of absorption resonances of rubidium atoms, a system which has proven its potential as long-lived and efficient quantum memory 45 . Moreover, the availability of downconversion techniques 46 in combination with methods to convert polarization entanglement into time-bin entanglement 47 48 make our QDs suited for quantum communication at telecom wavelengths. A key ingredient to achieve high single-photon purity, high two-photon interference and high level of entanglement is the two-photon resonant excitation.…”

Section: Discussionmentioning

confidence: 99%

Highly indistinguishable and strongly entangled photons from symmetric GaAs quantum dots

et al. 2017

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The development of scalable sources of non-classical light is fundamental to unlocking the technological potential of quantum photonics. Semiconductor quantum dots are emerging as near-optimal sources of indistinguishable single photons. However, their performance as sources of entangled-photon pairs are still modest compared to parametric down converters. Photons emitted from conventional Stranski–Krastanov InGaAs quantum dots have shown non-optimal levels of entanglement and indistinguishability. For quantum networks, both criteria must be met simultaneously. Here, we show that this is possible with a system that has received limited attention so far: GaAs quantum dots. They can emit triggered polarization-entangled photons with high purity (g(2)(0) = 0.002±0.002), high indistinguishability (0.93±0.07 for 2 ns pulse separation) and high entanglement fidelity (0.94±0.01). Our results show that GaAs might be the material of choice for quantum-dot entanglement sources in future quantum technologies.

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Section: Discussionmentioning

confidence: 99%

Highly indistinguishable and strongly entangled photons from symmetric GaAs quantum dots

et al. 2017

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“…In particular, intense research efforts using InAs semiconductor QDs have enabled the generation of triggered photon pairs at * mullera@usf.edu high rates and under electric pump in a monolithic semiconductor chip with a high degree of polarization entanglement [23,24]. Recently it was shown that such polarization entanglement can be converted into time-bin entanglement, with the polarization entanglement derived from the biexciton/exciton three-level system [25,26].…”

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confidence: 99%

Franson Interference Generated by a Two-Level System

2017

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We report a Franson interferometry experiment based on correlated photon pairs generated via frequency-filtered scattered light from a near-resonantly driven two-level semiconductor quantum dot. In contrast to spontaneous parametric down conversion and four-wave mixing, this approach can produce single pairs of correlated photons. We have measured a Franson visibility as high as 66%, which goes beyond the classical limit of 50% and approaches the limit of violation of Bell's inequalities (70.7%).Introduction-Entanglement is perhaps the most intriguing of all physical phenomena, and was famously challenged by Einstein, Podolsky and Rosen (EPR) in 1935 [1]. The EPR paradox led to Bell's inequalities [2] which were since tested by numerous experiments [3] including recent "loophole-free" tests [4][5][6] that have conclusively demonstrated that entanglement cannot be explained using local hidden variable theories.Most experiments have employed photons that are entangled in the energy and polarization degrees of freedom [7][8][9][10]. However, this method is known to be sensitive to polarization mode dispersion in optical fibers [11]. As an alternative, entanglement in the time-energy basis may be employed, wherein quantum information is encoded in the arrival time of photons, and long-distance fiber transmission over 300 km is possible [12]. The approach of using time-energy entangled photons was first formulated by Franson, with photon pairs created in an atomic decay process and two unbalanced interferometers [13]. Franson-type experiments have stimulated a plethora of research activities and have been extensively used for Bell tests in quantum optics [14][15][16].Today, entangled photon pairs for Franson experiments are primarily produced via spontaneous parametric down conversion (SPDC) or four-wave mixing (FWM), following two main methods. In time-energy experiments [17,18], a nonlinear medium is pumped by a continuous monochromatic laser and emission times of the photons have an uncertainty equal to the coherence time of the pump laser. On the other hand in time-bin experiments [14,19], a nonlinear medium is pumped by pulses that have previously passed through an unbalanced interferometer, leading to a "which-path" ambiguity in emission time. However, either method provides a nondeterministic pair generation, leading to limitations on the accuracy and security of quantum communication.Single-photon sources, based on single atoms, ions, impurity centers and quantum dots (QDs) [20], have emerged as alternatives [21,22], emitting no more than a single pair during any given cascade decay. In particular, intense research efforts using InAs semiconductor QDs have enabled the generation of triggered photon pairs at

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“…Direct timebin-encoded entanglement generation from quantum dots has the advantage that larger FSSs are acceptable [37] but this scheme cannot produce true on-demand entangled pairs without the addition of a metastable state [37,38] and is technically demanding due to the need for phase control between the early and late photons, which can only be achieved with resonant two-photon excitation [39,40]. Alternatively, in the approach favored here, qubit transcoder setups using asymmetric Mach-Zehnder interferometers (AMZIs) can be used to create timebin-entangled photons from polarization-entangled ones [41,42]; however, demonstrations of this principle using C-band QDs are still outstanding.…”

Section: Introductionmentioning

confidence: 99%