Micrometer-scale integrated silicon source of time-energy entangled photons

Grassani, Davide; Azzini, Stefano; Liscidini, Marco; Galli, Mattéo; Strain, Michael J.; Sorel, Marc; Sipe, J. E.; Bajoni, Daniele

doi:10.1364/optica.2.000088

Cited by 243 publications

(188 citation statements)

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“…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.…”

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confidence: 99%

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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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Franson Interference Generated by a Two-Level System

2017

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“…All together, these features potentially mark a substantial step forward to achieve stable, integrated, and CMOS- compatible multimode sources for quantum optical applications. While in this particular case only heralded single photons were generated, it has been shown that, for example, energy-time or time-bin entanglement can be generated using SFWM on chip [28,29]. In particular, by combining time-bin entanglement and the wavelength multiplexing approach, we recently demonstrated the generation of bi-and multiphoton-entangled qubits [30].…”

Section: Figmentioning

confidence: 97%

“…Since quantum memories are typically based on atomic transitions that have linewidths on the order of 10 to 100 MHz [25], the photon pairs must also exhibit these bandwidths. Many of the sources based on integrated resonators have so far failed to achieve the narrow linewidths compatible with quantum memories because of their relatively modest Q-factors [14,16,[26][27][28][29]. On the other hand, narrow linewidth sources can be achieved by exploiting extremely high Q-factor cavities, however these are fundamentally incompatible with large-scale integration [6,15,[31][32][33].…”

Section: Introductionmentioning

confidence: 99%

Multifrequency sources of quantum correlated photon pairs on-chip: a path toward integrated Quantum Frequency Combs

et al. 2016

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Recent developments in quantum photonics have initiated the process of bringing photonic-quantumbased systems out-of-the-lab and into real-world applications. As an example, devices to enable the exchange of a cryptographic key secured by the laws of quantum mechanics are already commercially available. In order to further boost this process, the next step is to transfer the results achieved by means of bulky and expensive setups into miniaturized and affordable devices. Integrated quantum photonics is exactly addressing this issue. In this paper, we briefly review the most recent advancements in the generation of quantum states of light on-chip. In particular, we focus on optical microcavities, as they can offer a solution to the problem of low efficiency that is characteristic of the materials typically used in integrated platforms. In addition, we show that specifically designed microcavities can also offer further advantages, such as compatibility with telecom standards (for exploiting existing fibre networks) and quantum memories (necessary to extend the communication distance), as well as giving a longitudinal multimode character for larger information transfer and processing. This last property (i.e., the increased dimensionality of the photon quantum state) is achieved through the ability to generate multiple photon pairs on a frequency comb, corresponding to the microcavity resonances. Further achievements include the possibility of fully exploiting the polarization degree of freedom, even for integrated devices. These results pave the way for the generation of integrated quantum frequency combs that, in turn, may find important applications toward the realization of a compact quantum-computing platform.

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“…In particular, solutions focusing on an integrated (on-chip) approach have been recently investigated and developed, including integrated quantum circuits, sources and detectors [7]. In contrast to waveguides, microring resonators [8] with narrow resonances and high Qfactors, offer an improvement in photon-pair generation efficiency, as well as a narrow photon-pair bandwidth, making them compatible with quantum optical devices (e.g. high temporal-resolution singlephoton detectors and quantum memories).…”

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confidence: 99%