Experimental implementation of quantum gates through actuator qubits

TL;DR

This paper demonstrates an alternative quantum gate implementation method using actuator qubits and a drift Hamiltonian, eliminating the need for local control on all qubits, with experiments on nuclear spins.

Contribution

It introduces a scheme for quantum gates that relies on indirect control via actuator qubits and a drift Hamiltonian, reducing the need for local control.

Findings

Successful implementation of one- and two-qubit gates on target qubits.

Experimental validation using nuclear spins and magnetic-dipole couplings.

Elimination of the need for local control on all qubits.

Abstract

Universal quantum computation requires the implementation of arbitrary control operations on the quantum register. In most cases, this is achieved by external control fields acting selectively on each qubit to drive single-qubit operations. In combination with a drift Hamiltonian containing interactions between the qubits, this allows the implementation of any required gate operation. Here, we demonstrate an alternative scheme that does not require local control for all qubits: we implement one- and two-qubit gate operations on a set of target qubits indirectly, through a combination of gates on directly controlled actuator qubits with a drift Hamiltonian that couples actuator and target qubits. Experiments are performed on nuclear spins, using radio-frequency pulses as gate operations and magnetic-dipole couplings for the drift Hamiltonian.