Quantum Interference of Electromechanically Stabilized Emitters in Nanophotonic Devices

Abstract

Photon-mediated coupling between distant matter qubits [1,2] may enable secure communication over long distances, the implementation of distributed quantum computing schemes, and the exploration of new regimes of many-body quantum dynamics [3,4]. Solidstate quantum emitters coupled to nanophotonic devices represent a promising approach towards these goals, as they combine strong light-matter interaction and high photon collection efficiencies [5-7]. However, nanostructured environments introduce mismatch and diffusion in optical transition frequencies of emitters, making reliable photon-mediated entanglement generation infeasible [7]. Here we address this long-standing challenge by employing silicon-vacancy (SiV) color centers embedded in electromechanically deflectable nanophotonic waveguides. This electromechanical strain control enables control and stabilization of optical resonance between two SiV centers on the hour timescale.Using this platform, we observe the signature of an entangled, superradiant state arising from quantum interference between two spatially separated emitters in a waveguide. This demonstration and the developed platform constitute a crucial step towards a scalable quantum network with solid state quantum emitters.

Experimental demonstration of memory-enhanced quantum communication

“…Experimental setup and device fabrication [19,33,36,37] for millikelvin nanophotonic cavity QED experiments with SiV centers are thoroughly described in a separate publication [38]. We perform all measurements in a dilution refrigerator (DR, BlueFors BF-LD250) with a base temperature of 20 mK.…”

“…The use of long-lived 13 C nuclear spin qubits could eliminate the need to operate at low total n m and would provide longer storage times, potentially enabling hundred-fold enhancement of BSM success rates [17,20]. Recently implemented strain-tuning capabilities [33] should allow for operation of many quantum nodes at Performance of memory-assisted quantum communication. Log-log plot of key rate in bits per channel use versus effective channel transmission (pA→B = n 2 p , where n p is the average number of photons incident on the measurement device per photonic qubit).…”

Coherent acoustic control of a single silicon vacancy spin in diamond

“…The SiV is a point defect in diamond that has attracted attention due to its excellent optical properties [19], longlived electronic spin qubit [10], and ability to maintain these properties inside nanoscale devices [20,21]. It is * loncar@seas.harvard.edu formed by a silicon atom located centrally between two adjacent vacant sites in the diamond lattice ( Fig.…”

Making Diamond Qubits Talk to Light

“…The work presented here and in the complementary letter [29] illustrates the path towards the realization of a firstgeneration quantum repeater based on SiV centers inside diamond nanodevices. We note that a key ingredient enabling future, large-scale experiments involving several solid-state SiV-nanocavity nodes will be the incorporation of strain tuning onto each device [67]. Precise tuning of both the static and dynamic strain can overcome the limitations of inhomogeneous broadening and spectral diffusion, and enable scalable fabrication of quantum repeater nodes (Sec.…”

“…12(b)]. Alternatively this signal could be used to actively stabilize the line using strain tuning [67,72]. From the observations in Fig.…”