Heralded Quantum Gates with Integrated Error Detection in Optical Cavities

Abstract

We propose and analyze heralded quantum gates between qubits in optical cavities. They employ an auxiliary qubit to report if a successful gate occurred. In this manner, the errors, which would have corrupted a deterministic gate, are converted into a non-unity probability of success: once successful the gate has a much higher fidelity than a similar deterministic gate. Specifically, we describe that a heralded , near-deterministic controlled phase gate (CZ-gate) with the conditional error arbitrarily close to zero and the success probability that approaches unity as the cooperativity of the system, C, becomes large. Furthermore, we describe an extension to near-deterministic Nqubit Toffoli gate with a favorable error scaling. These gates can be directly employed in quantum repeater networks to facilitate near-ideal entanglement swapping, thus greatly speeding up the entanglement distribution.

Universal quantum computation in waveguide QED using decoherence free subspaces

“…It originates from the trade-off between cancelling errors from spontaneous emitted photons and the ones coming from cavity/waveguide emission, which lead to the optimal scaling with -P 1D 1 2 . There have been proposed ways with atomic Λ systems for overcoming this error scaling either by using dissipative state preparation [39] or heralding measurements [40,41]. An interesting perspective of our proposal is how to extrapolate these ideas to the two-level emitter situation to overcome the -P 1D 1 2 scaling.…”

An integrated diamond nanophotonics platform for quantum-optical networks

“…Because of the large cavity bandwidth, more than ten coupled emitters can be addressed independently in a single cavity to form complex quantum nodes that efficiently couple to a fiber network. Such a system can be used to implement robust quantum gates for either photonic or spin qubits with integrated error detection and correction (42), paving the way for the realization of integrated quantum networks with applications such as long-distance quantum communication (1)(2)(3).…”

Large-scale quantum photonic circuits in silicon

“…For photons in integrated waveguide circuits, a sufficiently strong interaction may be possible using nonlinearities of single atom-like systems [1][2][3][4][5][6][7]. Photon loss and mode distortion [8,9] can cause gate errors, but heralded gates [10] may help. Alternatively, it was shown by Knill et al [11] that an effective nonlinear interaction between single photons can be produced by the act of measurement, enabling heralded probabilistic logic gates that can be sufficient, in principle, for faulttolerant quantum computing by using teleportation and feed-forward.…”