January 27, 2023

Entanglement from tensor networks on a trapped-ion QCCD quantum computer

The ability to selectively measure, initialize, and reuse qubits during a quantum circuit enables a mapping of the spatial structure of certain tensor-network states onto the dynamics of quantum circuits, thereby achieving dramatic resource savings when using a quantum computer to simulate many-body systems with limited entanglement.

A team of researchers has experimentally demonstrate da significant benefit of this approach to quantum simulation: In addition to all correlation functions, the entanglement structure of an infinite system — specifically the half-chain entanglement spectrum — is conveniently encoded within a small register of “bond qubits” and can be extracted with relative ease.

Using a trapped-ion QCCD quantum computer equipped with selective mid-circuit measurement and reset, they quantitatively determined the near-critical entanglement entropy of a correlated spin chain directly in the thermodynamic limit and show that its phase transition becomes quickly resolved upon expanding the bond-qubit register.

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