Microcavity controlled coupling of excitonic qubits

Abstract

Controlled non-local energy and coherence transfer enables light harvesting in photosynthesis and non-local logical operations in quantum computing. This process is intuitively pictured by a pair of mechanical oscillators, coupled by a spring, allowing for a reversible exchange of excitation. On a microscopic level, the most relevant mechanism of coherent coupling of distant quantum bits—like trapped ions, superconducting qubits or excitons confined in semiconductor quantum dots—is coupling via the electromagnetic field. Here we demonstrate the controlled coherent coupling of spatially separated quantum dots via the photon mode of a solid state microresonator using the strong exciton–photon coupling regime. This is enabled by two-dimensional spectroscopy of the sample’s coherent response, a sensitive probe of the coherent coupling. The results are quantitatively understood in a rigorous description of the cavity-mediated coupling of the quantum dot excitons. This mechanism can be used, for instance in photonic crystal cavity networks, to enable a long-range, non-local coherent coupling.

Cavity-Enhanced Transport of Charge

“…PACS numbers: 05.60. Gg, 42.50.Pq, 74.40.Gh, The study of strong light-matter interactions [1][2][3][4] is playing an increasingly crucial role in understanding as well as engineering new states of matter with relevance to the fields of quantum optics [5][6][7][8][9][10][11][12][13][14][15][16][17][18], solid state physics [19][20][21][22][23][24][25][26][27][28][29][30][31], as well as quantum chemistry [32][33][34][35][36] and material science [37][38][39][40][41][42][43][44][45][46][47][48][49][...…”

Multidimensional coherent optical spectroscopy of semiconductor nanostructures: a review

“…In particular, I am thinking about: TMDs [107], whose fundamental properties such as intrinsic homogeneous linewidth can be measured with MDCS ; semiconductor microcavities [59,101,69], where MDCS can help bringing insight into the rich physics of polariton-polariton interactions ; small ensembles of QDs [95,68], within which the control of coherent coupling mechanisms may open the way to scalable quantum information processors [2]. Furthermore, the recent development of photocurrent-based MDCS [71,76] promises to shed a new light on the nonlinear optical response of optoelectronic devices in operating conditions.…”

“…Further work with polarization resolution enabled the determination of polarization selection rules for quantum pathways involving biexcitons and fine-structure-splitted states in single QDs [95]. A similar experiment realised on InGaAs QDs embedded in a micro-pillar cavity demonstrated the cavity-mediated coherent coupling of up to three excitons confined in separated QDs [68]. If QD excitonic transitions are used as qubits, the coherent optical control and readout of a small ensemble QDs demonstrated in these contributions can be seen as an interesting step toward the implementation of quantum algorithms.…”

“…This issue can be circumvented by monitoring the phase of a two-level system of reference (e.g. a QD that is assumed to be isolated [65,68]) and post processing the data to revert the phase changes that occurred due to fluctuations of the optical path. It is thus difficult to use such a method when an isolated two-level system of reference is not available .…”

Laser from a many-body correlated medium

“…We suggest operational and measurable quantities where the many-body nature of the active medium naturally emerges through probing of the coherent radiation emitted from the lasing cavity. A natural implementation of the model analyzed in this paper can be envisioned for multiple quantum dots coupled to a semiconductor resonator [28][29][30], in particular in view of the recent success in fabricating site-controlled quantum dots [29,31,32]. Direct Coulomb-mediated coupling between semiconductor quantum dots in particular has been demonstrated in vertically aligned self-assembled quantum dots [33,34] and in distant quantum dots through coupling to an extended Coulomb complex [35].…”