Parity-dependent state transfer for direct entanglement generation

TL;DR

This paper demonstrates perfect quantum state transfer and multi-qubit entanglement generation in a superconducting qubit chain, highlighting the protocol's parity-dependent properties and its application in creating GHZ states.

Contribution

It experimentally implements perfect state transfer with tunable superconducting qubits, revealing parity-dependent interactions and enabling efficient entanglement generation.

Findings

Successful transfer of quantum states across six qubits

Verification of parity-dependent phase control

Preparation of GHZ state via state transfer

Abstract

As quantum information technologies advance, challenges in scaling and connectivity persist, particularly the need for long-range qubit connectivity and efficient entanglement generation. Perfect State Transfer enables time-optimal state transfer between distant qubits using only nearest-neighbor couplings, enhancing device connectivity. Moreover, the transfer protocol results in effective parity-dependent non-local interactions, extending its utility to entanglement generation. Here, we experimentally demonstrate Perfect State Transfer and multi-qubit entanglement generation on a chain of six superconducting transmon qubits with tunable couplers, controlled via parametric drives. By simultaneously activating and engineering all couplings, we implement the transfer for up to six qubits, verifying single-excitation dynamics for different initial states. Extending the protocol to multiple excitations, we confirm its parity-dependent nature, where excitation number controls the phase of the transferred state. Finally, leveraging this property, we prepare a Greenberger-Horne-Zeilinger state using a single transfer operation, showcasing the potential of Perfect State Transfer for efficient entanglement generation.