Study on a quantum interface connecting photon and spin using quantum dot

Shuo Sun, Edo Waks A

C. Millet

Jason S. Pelc, Leo Yu, Kristiaan De Greve +11 more

Long-distance quantum communication networks require appropriate interfaces between matter qubit-based nodes and low-loss photonic quantum channels. We implement a downconversion quantum interface, where the single photons emitted from a semiconductor quantum dot at 910 nm are downconverted to 1560 nm using a fiber-coupled periodically poled lithium niobate waveguide and a 2.2-μm pulsed pump laser. The single-photon character of the quantum dot emission is preserved during the downconversion process: we measure a cross-correlation g(2)(τ = 0) = 0.17 using resonant excitation of the quantum dot. We show that the downconversion interface is fully compatible with coherent optical control of the quantum dot electron spin through the observation of Rabi oscillations in the downconverted photon counts. These results represent a critical step towards a long-distance hybrid quantum network in which subsystems operating at different wavelengths are connected through quantum frequency conversion devices and 1.5-μm quantum channels.

Ataç İmamoğlu

Zeng, Zheng

Connecting quantum processors over long distances using photon qubits would enable more complex quantum computing architectures and quantum networks. Recently a protocol to transfer a quantum state from a photonic qubit to a singlet-triplet spin qubit in GaAs/AlGaAs heterostructure has been theoretically demonstrated. In practice, the coherent transfer is facilitated by a hybrid device where a GaAs/AlGaAs gate-defined quantum dot (GDQD) is tunnel coupled to a self-assembled quantum dot (SAQD), in which a conversion between a photon state and a spin state takes place. This work addressed the three requirements of the optical-interface devices based on tunnel coupling between the GDQD and the SAQD: (i) a properly designed GaAs/AlGaAs heterostructure where the two-dimensional electron gas (2DEG) can be electrically tuned into resonance with the InAs SAQD; (ii) high-mobility 2DEG to form and operate a GDQD; (iii) precise alignment between the SAQD and the GDQD. It is proven that the InAs SAQD can be tuned to be charged, discharged, and resonant with the 2DEG by applying a local electric field.

Weibo Gao, P. Fallahi, Emre Togan +2 more