Coherent control of spontaneous emission near a photonic band edge: A qubit for quantum computation

Woldeyohannes, Mesfin; John, Sajeev

doi:10.1103/physreva.60.5046

Cited by 143 publications

(159 citation statements)

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“…In fact, in real crystals with finite dimensions a pseudogap is typically obtained where the density of states is strongly smaller than that of free space but is not exactly zero. In such gaps, however, the lowering of the local density of states can be so large that the spontaneous decay of an excited emitter is effectively inhibited so that memory and coherent control effects are admitted and similar to those occurring in an ideal PBG [17,18,19]. This would correspond, in view of the relation between population and entanglement expressed by Eqs.…”

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Entanglement trapping in structured environments

et al. 2008

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The entanglement dynamics of two independent qubits each embedded in a structured environment under conditions of inhibition of spontaneous emission is analyzed, showing entanglement trapping. We demonstrate that entanglement trapping can be used efficiently to prevent entanglement sudden death. For the case of realistic photonic band-gap materials, we show that high values of entanglement trapping can be achieved. This result is of both fundamental and applicative interest since it provides a physical situation where the entanglement can be preserved and manipulated, e.g. by Stark-shifting the qubit transition frequency outside and inside the gap.PACS numbers: 03.67. Mn, 03.65.Yz, 71.55.Jv Entanglement preservation is an important challenge in quantum information and computation technologies [1]. Realistic quantum systems are affected by decoherence and entanglement losses because of the unavoidable interaction with their environments [2]. For example in Markovian (memoryless) environments, in spite of an exponential decay of the single qubit coherence, the entanglement between two qubits may completely disappear at a finite time [3,4]. This phenomenon, known as "entanglement sudden death" and proven to occur in a quantum optics experiment [5], in turn limits the time when entanglement could be exploited for practical purposes. It is therefore of interest to examine the possibility to preserve entanglement. In the case of environments with memory (non-Markovian), such as imperfect cavities supporting a mode resonant with the atomic transition frequency, revivals of two-qubit entanglement have been found [6,7,8]. These revivals, although effectively extending the possible usage time of entanglement, decrease with time and eventually disappear after a certain critical time. Moreover, when the qubits interact with a common environment, it has been shown that entanglement can be preserved by means of the quantum Zeno effect [8].In this paper we continue the investigation on physical systems and physical effects that may lead to effective long time entanglement protection. Since entanglement evolution and population decay have been previously shown to be related [7], one is led to investigate situations where population trapping occurs. This can happen in structured environments where the density of states presents a dip which can inhibit spontaneous emission in the region of the dip [9]. Among realistic physical situations, this effect is known to occur in photonic band-gap (PBG) materials [10]. Entanglement can be generated when a pair of atoms near-resonantly coupled to the edge of a PBG present direct dipole-dipole interaction [11]. On the other hand, a way to produce entangled independent atoms in PBG materials is to consider a three-dimensional photonic crystal single-mode cavity with a sufficiently high-quality Q factor where Rydberg atoms can freely travel through the connected void regions [12]. The atoms exchange photons with the cavity, represented by a single defect mode of the crystal resonant with t...

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“…In many experiments the qubits are mimicked by "artificial atoms" consisting in quantum dot structures embedded in the solid fraction of the PBG material [19,22]. Quantum dots permit the coherent manipulation of a single localized quantum system with the technological advantages of solid-state systems.…”

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Entanglement trapping in structured environments

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“…The PhC is a one-, two-, or three-dimensional structure with a periodically modulated dielectric function and whose period of modulation is on the order of the optical wavelength. The optical characteristics of PhCs have profound implications for light localization [7], quantum state generation [8], high efficiency microlasers [9], optical sensors [10,11], and a wide range of photonic devices [12].…”

Section: Introductionmentioning

confidence: 99%

Superradiance in a Two-Dimensional Photonic Bandgap Structure

Mel’nikov

Haus

Aitchison

2006

IEEE J. Select. Topics Quantum Electron.

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-We study the superradiant decay of an ensemble of inverted two-level atoms embedded into both a continuous dielectric and a 2D photonic crystal with lateral confinement of the radiation. The nonlinear superradiance pulse characteristics are calculated using a Green function based model. Specifically, we predict fast phase synchronization across the ensemble that builds up a distributed feedback structure responsible for the superradition anisotropy and directional switching. We show that the transfer of the optical excitation takes place along the Bragg planes and is manifested by strong energy localization.

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“…In general, the light confinement is accompanied by an anomalously large vacuum Rabi splitting. Furthermore, Rabi splitting causes the formation of several localized modes in confined light (M. Woldeyohannes et al 1999). It is increasingly desired to form confined light composed of a single localized mode.…”

Section: Introductionmentioning

confidence: 99%

Confined light composed of a single localized mode inside photonic crystals for a qubit

Nihei

Okamoto

2012

Opt Quant Electron

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We have demonstrated that light is confined in a single mode near a very small defect (such as an impurity atom) embedded in photonic crystals by coherent control using a dark line that is a spectrum singularity leading to the complete quenching of emission. In this demonstration, we have clarified the strong confinement and a very short response time, as compared with the widely used tunable PBG method. These features are useful for keeping the memory in a two-state quantum system such as a quantum bit (qubit) and for processing quantum information.

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Coherent control of spontaneous emission near a photonic band edge: A qubit for quantum computation

Cited by 143 publications

References 72 publications

Entanglement trapping in structured environments

Entanglement trapping in structured environments

Superradiance in a Two-Dimensional Photonic Bandgap Structure

Confined light composed of a single localized mode inside photonic crystals for a qubit

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