Limitations of two-level emitters as nonlinearities in two-photon controlled-phase gates

Nysteen, Anders; McCutcheon, Dara P. S.; Heuck, Mikkel; Mørk, Jesper; Englund, Dirk

doi:10.1103/physreva.95.062304

Cited by 19 publications

(24 citation statements)

References 53 publications

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“…Since we have a particular interest in two-qubit logic gates for quantum information processing, we consider cavity configurations enabling a c-phase gate. Note that we envision a configuration where two identical cavities are placed in between two 50/50 beam-splitters that convert the two-qubit state |11 into 1/ √ 2(|02 +|20 ) [21,22]. In this case, the phase θ n in Eq.…”

Section: Nonlinear Dynamicsmentioning

confidence: 99%

Photon-photon interactions in dynamically coupled cavities

2020

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We study theoretically the interaction between two photons in a nonlinear cavity. The photons are loaded into the cavity via a method we propose here, in which the input/output coupling of the cavity is effectively controlled via a tunable coupling to a second cavity mode that is itself strongly output-coupled. Incoming photon wave packets can be loaded into the cavity with high fidelity when the timescale of the control is smaller than the duration of the wave packets. Dynamically coupled cavities can be used to avoid limitations in the photon-photon interaction time set by the delay-bandwidth product of passive cavities. Additionally, they enable the elimination of wave packet distortions caused by dispersive cavity transmission and reflection. We consider three kinds of nonlinearities, those arising from χ (2) and χ (3) materials and that due to an interaction with a two-level emitter. To analyze the input and output of few-photon wave packets we use a Schrödingerpicture formalism in which travelling-wave fields are discretized into infinitesimal time-bins. We suggest that dynamically coupled cavities provide a very useful tool for improving the performance of quantum devices relying on cavity-enhanced light-matter interactions such as single-photon sources and atom-like quantum memories with photon interfaces. As an example, we present simulation results showing that high fidelity two-qubit entangling gates may be constructed using any of the considered nonlinear interactions.

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Section: Nonlinear Dynamicsmentioning

confidence: 99%

Photon-photon interactions in dynamically coupled cavities

2020

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“…Photons with time-symmetric wave packets are particularly interesting for e.g. two-photon gates [30] and reducing sensitivity to timing jitter in two-photon interference [31] so we consider a Gaussian wave packet as a specific example…”

Section: Photon Frequency Conversionmentioning

confidence: 99%

Unidirectional frequency conversion in microring resonators for on-chip frequency-multiplexed single-photon sources

et al. 2019

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Microring resonators are attractive for low-power frequency conversion via Bragg-scattering fourwave-mixing due to their comb-like resonance spectrum, which allows resonant enhancement of all four waves while maintaining energy and momentum conservation. However, the symmetry of such mode structures limits the conversion efficiency to 50% due to the equal probability of up-and downconversion. Here, we demonstrate how two coupled microrings enable highly directional conversion between the spectral modes of one of the rings. An extinction between up-and down-conversion of more than 40 dB is experimentally observed. Based on this method, we propose a design for on-chip multiplexed single-photon sources that probabilistically generate photon pairs across many frequency modes of a ring resonator and subsequently convert them to a single frequency-thereby enabling quasi-deterministic photon emission. Our numerical analysis shows that once a photon is generated, it can be converted and emitted into a wave packet having a 90% overlap with a Gaussian with 99% efficiency for a ratio between intrinsic and coupling quality factors of 400.

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“…6(a). However, by using a beamsplitter and taking advantage of the Hong-Ou-Mandel effect we can construct a photon-photon gate out of two self-Kerr nonlinearities [7,8], as in Fig. 6(b).…”

Section: Application To Two-qubit Gatesmentioning

confidence: 99%

“…6(a), directly implements a CPHASE gate. The standard way [7,8] to implement the same gate using a self-Kerr interaction is shown in Fig. 6(b).…”

Section: Application To Two-qubit Gatesmentioning

confidence: 99%

“…Finally we use our multimode self-Kerr medium to construct a nonlinear sign shift gate [7]. We were motivated by the recent proposal of Nysteen et al [8] which achieved a fidelity of F = 0.84 with two two-level emitters. Here we show we show that with three sites (which could be constructed from a total of six 3-level atoms) we get F = 0.95 and generally we can approach F = 1 as the number of sites increases.…”

Section: Introductionmentioning

confidence: 99%

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Two-photon self-Kerr nonlinearities for quantum computing and quantum optics

Combes

Brod

2018

Phys. Rev. A

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The self-Kerr interaction is an optical nonlinearity that produces a phase shift proportional to the square of the number of photons in the field. At present, many proposals use nonlinearities to generate photon-photon interactions. For propagating fields these interactions result in undesirable features such as spectral correlation between the photons. Here, we engineer a discrete network composed of cross-Kerr interaction regions to simulate a self-Kerr medium. The medium has effective long-range interactions implemented in a physically local way. We compute the one-and two-photon S matrices for fields propagating in this medium. From these scattering matrices we show that our proposal leads to a high fidelity photon-photon gate. In the limit where the number of nodes in the network tends to infinity, the medium approximates a perfect self-Kerr interaction in the one-and two-photon regime.

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Limitations of two-level emitters as nonlinearities in two-photon controlled-phase gates

Cited by 19 publications

References 53 publications

Photon-photon interactions in dynamically coupled cavities

Photon-photon interactions in dynamically coupled cavities

Unidirectional frequency conversion in microring resonators for on-chip frequency-multiplexed single-photon sources

Two-photon self-Kerr nonlinearities for quantum computing and quantum optics

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