Quantum Computation of Frequency-Domain Molecular Response Properties Using a Three-Qubit iToffoli Gate

Understand

The quantum computation of molecular response properties on near-term quantum hardware is a topic of significant interest.

• While computing time-domain response properties is in principle straightforward due to the natural ability of quantum computers to simulate unitary time evolution, circuit depth limitations restrict the maximum time that can be simulated and hence the extraction of frequency-domain properties.
• Computing properties directly in the frequency domain is therefore desirable, but the circuits require large depth when the typical hardware gate set consisting of single- and two-qubit gates is used.
• Here, we report the experimental quantum computation of the response properties of diatomic molecules directly in the frequency domain using a three-qubit iToffoli gate, enabling a reduction in circuit depth by a factor of two.