Bell state generation and CNOT operation using on-demand identical photons from shape-controlled spatially ordered quantum dots

TL;DR

This paper demonstrates a two-qubit CNOT gate and Bell state generation using photons from shape-controlled quantum dots, advancing scalable on-chip photonic quantum computing.

Contribution

It introduces the use of mesa-top single quantum dots in regular arrays for deterministic photon generation and quantum gate operations.

Findings

Achieved Bell state fidelity of 0.825 with high photon interference visibility.

Demonstrated CNOT gate operation using photons from individual quantum dots.

Results support development of quantum dot arrays for scalable quantum information processing.

Abstract

Fault tolerant on-chip photonic quantum computation is enormously helped by (a) deterministic generation of the needed thousands to millions of photon qubits from (b) quantum emitters in designed spatially ordered arrays to enable networks for implementing many-qubit logic circuits. Scaling up photonic quantum information processing systems has, however, been prevented by the lack of such quantum emitters until the demonstration of the platform of mesa-top single quantum dots (MTSQDs) -- controlled shape, size, and volume single QD -- located in designed regular arrays. Here we demonstrate 2 qubit CNOT gate operation -- a universal gate necessary to enable quantum circuits of arbitrary complexity -- in polarization basis using photons emitted from individual MTSQDs. A Bell state fidelity of 0.825$\pm$0.010 is achieved with two photon interference (TPI) visibility of 0.947$\pm$0.0015 at 4K without Purcell enhancement. The results make a strong case for developing MTSQD arrays for utility scale optical quantum information processing platforms.