Cavity assisted emission of single, paired and heralded photons from a single quantum dot device

Bell states are the most prominent maximally entangled photon states. In a typical four‐level emitter, like a semiconductor quantum dot, the photon states exhibit only one type of Bell state entanglement. By adding an external driving to the emitter system, also other types of Bell state entanglement are reachable without changing the polarization basis. In this work, it is shown under which conditions the different types of entanglement occur and analytical equations are given to explain these findings. Furthermore, special points are identified, where the concurrence, being a measure for the degree of entanglement, drops to zero, while the coherences between the two‐photon states stay strong. Results of this work pave the way to achieve a controlled manipulation of the entanglement type in practical devices.

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“…However, considering the out‐coupling of light out of the cavity to be a Markovian process, Equation (16) can also describe

G_{j k, l m}^{(2)} false(t, τ false)

measured outside the cavity. [ 10,30 ]…”

Section: Photon Entanglementmentioning

confidence: 99%

Different Types of Photon Entanglement from a Constantly Driven Quantum Emitter Inside a Cavity

et al. 2020

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“…Fock as well as entangled photon states are integral ingredients of innovative developments [221], e.g. in quantum cryptography [222,223], quantum information processing [224][225][226] and photonics [227]. Furthermore, embedding a QD in a cavity it becomes possible to enter the strong coupling regime, where the quantum states of the QD and the cavity photons are tied together in coherent superpositions.…”

Section: Impact Of Carrier-phonon Interaction On Photonic Propertiesmentioning

confidence: 99%

Distinctive characteristics of carrier-phonon interactions in optically driven semiconductor quantum dots

Reiter

Kuhn

Axt

2019

Advances in Physics: X

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We review distinct features arising from the unique nature of the carrier-phonon coupling in self-assembled semiconductor quantum dots. Because of the discrete electronic energy structure, the pure dephasing coupling usually dominates the phonon effects, of which two properties are of key importance: The resonant nature of the dot-phonon coupling, i.e. its nonmonotonic behavior as a function of energy, and the fact that it is of super-Ohmic type. Phonons do not only act destructively in quantum dots by introducing dephasing, they also offer new opportunities, e.g. in state preparation protocols. Apart from being an interesting model systems for studying fundamental physical aspects, quantum dot and quantum dot-microcavity systems are a hotspot for many innovative applications. We discuss recent developments related to the decisive impact of phonons on key figures of merit of photonic devices like single or entangled photon sources under aspects like indistinguishability, purity and brightness. All in all it follows that understanding and controlling the carrier-phonon interaction in semiconductor quantum dots is vital for their usage in quantum information technology.

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“…Due to the one-to-one correspondence between two-time correlation functions of photon operators inside and outside the cavity shown in Ref. 33, the comparison between C(t), C, and C can also be interpreted in terms of the photons recorded in the two detectors used in coincidence measurement. Since the photons outside the cavity propagate with the speed of light they can be recorded at a given time in one of the detectors only when they have been emitted from the cavity at a retarded time that matches the flight time between cavity and detector.…”

Section: B Concurrencesmentioning

confidence: 99%

Comparison of different concurrences characterizing photon pairs generated in the biexciton cascade in quantum dots coupled to microcavities

et al. 2018

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We compare three different notions of concurrence to measure the polarization entanglement of two-photon states generated by the biexciton cascade in a quantum dot embedded in a microcavity. The focus of the paper lies on the often-discussed situation of a dot with finite biexciton binding energy in a cavity tuned to the two-photon resonance. Apart from the time-dependent concurrence, which can be assigned to the two-photon density matrix at any point in time, we study single-and double-time integrated concurrences commonly used in the literature that are based on different quantum state reconstruction schemes. In terms of the photons detected in coincidence measurements, we argue that the single-time integrated concurrence can be thought of as the concurrence of photons simultaneously emitted from the cavity without resolving the common emission time, while the more widely studied double-time integrated concurrence refers to photons that are neither filtered with respect to the emission time of the first photon nor with respect to the delay time between the two emitted photons. Analytic and numerical calculations reveal that the single-time integrated concurrence indeed agrees well with the typical value of the time-dependent concurrence at long times, even when the interaction between the quantum dot and longitudinal acoustic phonons is accounted for. Thus, the more easily measurable single-time integrated concurrence gives access to the physical information represented by the time-dependent concurrence. However, the doubletime integrated concurrence shows a different behavior with respect to changes in the exciton fine structure splitting and even displays a completely different trend when the ratio between the cavity loss rate and the fine structure splitting is varied while keeping their product constant. This implies the non-equivalence of the physical information contained in the time-dependent and single-time integrated concurrence on the one hand and the double-time integrated concurrence on the other hand.arXiv:1712.02584v3 [cond-mat.mes-hall] 9 May 2018

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Cavity assisted emission of single, paired and heralded photons from a single quantum dot device

Cited by 20 publications

References 40 publications

Different Types of Photon Entanglement from a Constantly Driven Quantum Emitter Inside a Cavity

Different Types of Photon Entanglement from a Constantly Driven Quantum Emitter Inside a Cavity

Distinctive characteristics of carrier-phonon interactions in optically driven semiconductor quantum dots

Comparison of different concurrences characterizing photon pairs generated in the biexciton cascade in quantum dots coupled to microcavities

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