Cavity-stimulated Raman emission from a single quantum dot spin

Abstract

Solid state quantum emitters have shown strong potential for applications in quantum information, but spectral inhomogeneity of these emitters poses a significant challenge. We address this issue in a cavity-quantum dot system by demonstrating cavity-stimulated Raman spin flip emission. This process avoids populating the excited state of the emitter and generates a photon that is Raman shifted from the laser and enhanced by the cavity. The emission is spectrally narrow and tunable over a range of at least 125 GHz, which is two orders of magnitude greater than the natural linewidth. We obtain the regime in which the Raman emission is spin-dependent, which couples the photon to a long-lived electron spin qubit. This process can enable an efficient, tunable source of indistinguishable photons and deterministic entanglement of distant spin qubits in a photonic crystal quantum network.Controlled absorption and emission of single photons by quantum emitters are essential processes for quantum information technologies. Single photons can be used to transfer quantum information from one stationary qubit to another as part of a quantum network 1-4 , or they can be used as a qubit for photonic quantum computing 5 or secure communication 6 . Currently the largest challenge in achieving these goals is in scaling up the number of qubits. A promising approach is the integration of solid state quantum emitters into a photonic architecture [7][8][9] . Candidate materials include quantum dots 7,8 (QDs), QD molecules 10-13 , nitrogen-vacancy centers in diamond 9,14 , and other impurities or defects in solids 15,16 . These materials can take advantage of nanofabrication technologies to produce monolithic integrated structures that simplify the scaling-up problem 7,9 . Unfortunately, solid state quantum emitters suffer from spectral inhomogeneity, which greatly limits their usefulness for protocols that involve identical photons 5 or that involve the exchange of a photon between two qubits 1-4 .Here we demonstrate for the first time in a solid state system a cavity-stimulated Raman process [17][18][19] that can be used to overcome spectral inhomogeneity. We do this by coupling a negatively charged InAs/GaAs quantum dot (QD) that acts as a -type quantum emitter to a photonic crystal defect cavity 20 . Most previous work on QDs in cavities involves the coupling of 2 a 2-level exciton system to a cavity 7,[21][22][23] . In contrast, the three level -type system here provides a long-lived ground state electron spin coherence 24,25 , with ultrafast optical gates [25][26][27][28] and cavityenhanced initialization and readout 20 . The key feature of the Raman process (see Fig. 1a) is that the frequency of the emitted Raman photon is determined by the laser photon energy and the Zeeman energy, not by the excited state energy of the quantum emitter. The cavity strongly enhances this process when the Raman photon is resonant with the cavity mode. We measure cavity-stimulated Raman photons detuned from the QD over a range of at least 0.5 me...

An integrated diamond nanophotonics platform for quantum-optical networks

“…This approach can further be used to control the timing and the shape of the single-photon pulses (30). Unlike previous demonstrations of Raman tuning of solid-state quantum emitters (31)(32)(33), the tuning range demonstrated here (20) is comparable to the inhomogeneous distribution of the SiV ensemble and can thus be used to tune pairs of SiV centers into resonance. Entanglement of SiV centers in a diamond nanophotonic waveguide.…”

Screening Nuclear Field Fluctuations in Quantum Dots for Indistinguishable Photon Generation

“…Taken in isolation, Raman scattering from a QD with a resident electron or hole can have several attractive features. First, below saturation, the coherence of the Raman photons is determined by the ground-state dephasing rather than that of the excited state [18][19][20].Second, Raman photons are highly tunable: their energy is determined by the detuning of the driving field rather than the fundamental optical transition energy [18,20,21]. Finally, because of clean selection rules in QDs, the polarization of the Raman scattered photons can be linked to the spin of the final state [20][21][22], enabling spin-photon entanglement [23][24][25] and raising the prospect for quantum networks [26].…”

Single-shot optical readout of a quantum bit using cavity quantum electrodynamics

“…However realizing single-shot readout operation in Voigt configuration is more desired because this geometry is the prerequisite for all-optical coherent spin manipulation 37,38 . This geometry has also enabled lots of important applications including fast optical cooling 39,40 , coherent population trapping 41 , tunable Raman fluorescence [42][43][44] , and spin-photon entanglement [45][46][47][48] . couple to orthogonal polarization components of an optical field, denoted V and H respectively.…”