Dynamical qubit cooling via quasi-particle transport

Abstract

Cooling a quantum state presents a challenge as the external control in active protocols can induce detrimental heating in the system. Passive cooling processes offer a valuable alternative: Here, we present a simple quench protocol to cool a set of qubits with access to an ancillary spin chain. We show that excitations can be transported out of the qubits as quasi-particles, taking the form of magnons in a ferromagnetic ancilla and triplons in a dimerized antiferromagnetic ancilla. This quasi-particle transport mechanism enables cooling towards both individual and highly entangled two-qubit target states. We demonstrate that this cooling mechanism remains robust starting from thermal states and with finite quench ramp times.