Continuous dynamical decoupling of spin chains: Inducing two-qubit interactions to generate perfect entanglement

Abstract

Efficient control over entanglement in spin chains is useful for quantum information processing applications. In this paper, we propose the use of a combination of staggered and constant configurations of strong static and oscillating fields to control and generate perfect entanglement in a spin chain. While both staggered and constant configurations of control fields decouple the chain from the environment, a constant configuration also modulates the spin chain Hamiltonian, as a result of which spins in the chain continue to interact with each other. We show that a staggered configuration suppresses the spin-spin interactions in a chain, allowing us to use a constant configuration at particular sites in order to induce two-qubit interactions. With insight from numerical simulations, we analytically show that a series of two-qubit interactions, if applied for appropriate durations in a specific sequence, can be used to perfectly entangle any two spins in the XY chain. We show numerically how the scheme can be used for models without the need to solve them analytically.

Transforming spin chains with a continuous driving field

“…For instance, in some cases, the use of oscillatory and static control fields can effectively introduce additional spin-spin interaction terms which can in turn improve entanglement generation [32][33][34][35]. Similarly, a staggered field configuration has been shown to produce perfect entanglement between any two spin sites of an XY spin chain [36]. Second, control fields can be used to dynamically decouple the system from the environment so that the effect of noise on the spin chain is mitigated [37][38][39][40][41], thereby helping to protect the fragile quantum states from decoherence.…”