Extended linear regime of cavity-QED enhanced optical circular birefringence induced by a charged quantum dot

Abstract

General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/pure/about/ebr-terms PHYSICAL REVIEW B 91, 075304 (2015) Extended linear regime of cavity-QED enhanced optical circular birefringence induced by a charged quantum dot Giant optical Faraday rotation (GFR) and giant optical circular birefringence (GCB) induced by a single quantum-dot spin in an optical microcavity can be regarded as linear effects in the weak-excitation approximation if the input field lies in the low-power limit [Hu et al., Phys. Rev. B 78, 085307 (2008); 80, 205326 (2009)]. In this work, we investigate the transition from the weak-excitation approximation moving into the saturation regime comparing a semiclassical approximation with the numerical results from a quantum optics toolbox [Tan, J. Opt. B 1, 424 (1999)]. We find that the GFR and GCB around the cavity resonance in the strong-coupling regime are input field independent at intermediate powers and can be well described by the semiclassical approximation. Those associated with the dressed state resonances in the strong-coupling regime or merging with the cavity resonance in the Purcell regime are sensitive to input field at intermediate powers, and cannot be well described by the semiclassical approximation due to the quantum-dot saturation. As the GFR and GCB around the cavity resonance are relatively immune to the saturation effects, the rapid readout of single-electron spins can be carried out with coherent state and other statistically fluctuating light fields. This also shows that high-speed quantum entangling gates, robust against input power variations, can be built exploiting these linear effects.

Quantum correlations of light and matter through environmental transitions

“…they remain in a product state. In the weak driving limit, we may further assume that on average the TLE remains close to its ground state, such that σ z ≈ −1 [17,41]. For a sufficiently lossy cavity, the resulting semiclassical theory agrees perfectly with the atomic QOME, as is demonstrated by the points in Fig.…”

“…1(b)]. However, unlike the true QSC regime (in which g > κ + κ s , γ), the broad cavity transition obscures contributions from higher order dressed states, allowing an effective semiclassical description to be derived [16,17]. The double dip structure may then be interpreted simply as a normal mode splitting between two classical oscillators, rather than a signature of quantum light-matter correlations.…”

“…The broad cavity lineshape that results masks contributions from higher order dressed states. This places the system in an intermediate coupling regime that can be described using semiclassical techniques [17], thus neglecting all quantum correlations between the cavity photonic (light) and emitter electronic (matter) degrees of freedom. In addition to interactions with external electromagnetic fields, many CQED systems are also in contact with their host (e.g.…”

Limits to coherent scattering and photon coalescence from solid-state quantum emitters

“…This is in clear contrast to the atomic case, constituting a non-standard regime of semiconductor quantum optics. It is also of direct practical importance, for example, to light-matter coupling schemes that rely on the coherent scattering of photons with high efficiency [39,40]. Furthermore, we show that the impact of the phonon relaxation process can be even more pronounced in two-photon interference experiments, resulting in a substantial suppression of the photon coalescence visibility on picosecond time scales, which is exacerbated when accounting for the inevitable detector temporal response.…”

“…They thus have a profound impact on the level of coherently and incoherently scattered light, limiting the coherent fraction to values of ≈90% at T = 4 K. Moreover, when accounting for any realistic detector response time, these short-time phonon relaxation processes act to decrease two-photon HOM interference visibilities. These results have important implications for numerous quantum technology applications where an efficient source of coherently scattered photons is needed as a resource [39,40]. We stress that although our calculations have been formulated in the context of QDs, the results are expected to be applicable to a variety of solid-state emitters, including nitrogen vacancy centers [60], superconducting qubits, and dye molecules embedded in crystalline lattices [61,62].…”