Simulating Electronic Structure on Bosonic Quantum Computers.

Area of Science:

• Quantum Computing
• Quantum Chemistry
• Quantum Simulation

Background:

• Quantum harmonic oscillators (qumodes) offer a versatile framework for quantum computing due to their infinite-dimensional Hilbert space.
• Qubits are limited to two discrete levels, whereas qumodes are better suited for complex quantum simulations.
• The molecular electronic structure problem is a key challenge in computational chemistry requiring advanced simulation techniques.

Purpose of the Study:

• To propose and demonstrate a novel approach for mapping molecular electronic structures onto a qumode bosonic problem.
• To utilize bosonic quantum devices and the variational quantum eigensolver (VQE) for solving these problems.
• To compute ground potential energy surfaces for benchmark molecular systems.

Main Methods:

• Mapping the electronic Hamiltonian of molecules to a qumode bosonic Hamiltonian.
• Employing the variational quantum eigensolver (VQE) algorithm on bosonic quantum devices.
• Utilizing universal ansatzes like echoed conditional displacement (ECD) and selective number-dependent arbitrary phase (SNAP) operations for state preparation and expectation value computation.
• Leveraging circuit quantum electrodynamics (cQED) platforms for hardware implementation.

Main Results:

• Successfully computed ground potential energy surfaces for H2 and linear H4 molecules.
• Demonstrated the feasibility of the proposed qumode-based approach for molecular simulations.
• Showcased the compatibility of ECD and SNAP operations with cQED platforms.

Conclusions:

• The proposed method establishes a new pathway for simulating many-fermion systems using qumode bosonic quantum devices.
• Hybrid qubit-qumode quantum devices show significant potential for advancing quantum computational chemistry.
• This work paves the way for more accurate and efficient quantum simulations of molecular electronic structures.