Long-range exchange interaction between spin qubits mediated by a superconducting link at finite magnetic field

Exchange interaction of two spin qubits mediated by a superconductor

Entangling two quantum bits by letting them interact is the crucial requirement for building a quantum processor. For qubits based on the spin of the electron, these two qubit gates are typically performed by exchange interaction of the electrons captured in two nearby quantum dots. Since the exchange interaction relies on tunneling of the electrons, the range of interaction for conventional ap...

Ultra-long distance interaction between spin qubits

We describe a method for implementing deterministic quantum gates between two spin qubits separated by centimeters. Qubits defined by the singlet and triplet states of two exchange coupled quantum dots have recently been shown to possess long coherence times. When the effective nuclear fields in the two asymmetric quantum dots are different, total spin will no longer be a good quantum number an...

Long-range spin-qubit interaction mediated by microcavity polaritons.

We study the optically induced coupling between spins mediated by polaritons in a planar microcavity. In the strong-coupling regime, the vacuum Rabi splitting introduces anisotropies in the spin coupling. Moreover, due to their photonlike mass, polaritons provide an extremely long spin coupling range. This suggests the realization of two-qubit all-optical quantum operations within tens of picos...

Long range magnetic interaction between Josephson junctions.

A field-theoretical approach to the spin glass transition: models with long but finite interaction range

We study spin glasses with the Kac-type interaction potential for small but finite inverse interaction range γ. Using the theoretical set-up of coupled replicas, through the replica method we argue that the probability of overlap profiles can be expressed for small γ through a large deviation functional. This result is supported by rigorous arguments, showing that the large deviation functional...