We study two different methods to prepare excited states on a quantum computer, a key initial step to study nuclear dynamics within linear-response theory. The first method uses unitary evolution for a short time T=O(1-F) to approximate the action of an excitation operator Ô with fidelity F and success probability P≈1-F. The second method probabilistically applies the excitation operator using the linear combination of unitaries (LCU) algorithm. We benchmark these techniques on emulated and real quantum devices, using a toy model for thermal neutron-proton capture. Despite its larger-memory footprint, the LCU-based method is efficient even on current generation noisy devices and can be implemented at a lower gate cost than a naive analysis would suggest. These findings show that quantum techniques designed to achieve good asymptotic scaling on fault-tolerant quantum devices might also provide practical benefits on devices with limited connectivity and gate fidelity.

Preparation of excited states for nuclear dynamics on a quantum computer / Roggero, Alessandro; Gu, Chenyi; Baroni, Alessandro; Papenbrock, Thomas. - In: PHYSICAL REVIEW C. - ISSN 2469-9985. - 102:6(2020), pp. 064624.1-064624.23. [10.1103/PhysRevC.102.064624]

Preparation of excited states for nuclear dynamics on a quantum computer

Roggero, Alessandro;
2020

Abstract

We study two different methods to prepare excited states on a quantum computer, a key initial step to study nuclear dynamics within linear-response theory. The first method uses unitary evolution for a short time T=O(1-F) to approximate the action of an excitation operator Ô with fidelity F and success probability P≈1-F. The second method probabilistically applies the excitation operator using the linear combination of unitaries (LCU) algorithm. We benchmark these techniques on emulated and real quantum devices, using a toy model for thermal neutron-proton capture. Despite its larger-memory footprint, the LCU-based method is efficient even on current generation noisy devices and can be implemented at a lower gate cost than a naive analysis would suggest. These findings show that quantum techniques designed to achieve good asymptotic scaling on fault-tolerant quantum devices might also provide practical benefits on devices with limited connectivity and gate fidelity.
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Roggero, Alessandro; Gu, Chenyi; Baroni, Alessandro; Papenbrock, Thomas
Preparation of excited states for nuclear dynamics on a quantum computer / Roggero, Alessandro; Gu, Chenyi; Baroni, Alessandro; Papenbrock, Thomas. - In: PHYSICAL REVIEW C. - ISSN 2469-9985. - 102:6(2020), pp. 064624.1-064624.23. [10.1103/PhysRevC.102.064624]
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11572/312965
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