Chemically Accurate Potential Curves for H₂ Molecules Using Explicitly Correlated Qubit-ADAPT.

Area of Science:

• Quantum computing
• Computational chemistry
• Quantum algorithms

Background:

• Near-term quantum devices require efficient algorithms for practical applications.
• Variational quantum eigensolver (VQE) algorithms are promising for molecular energy calculations.
• The ADAPT approach enhances VQE with dynamically growing ansätze.

Purpose of the Study:

• To combine the ADAPT algorithm with a first-quantized formulation for the hydrogen molecule.
• To investigate the use of explicitly correlated basis functions for molecular simulations.
• To assess the feasibility of achieving chemical accuracy with near-term quantum devices.

Main Methods:

• Implementation of the ADAPT algorithm within a first-quantized framework.
• Utilizing explicitly correlated basis functions for the hydrogen molecule under the Born-Oppenheimer approximation.
• Performing classically simulated quantum computations to determine potential energy curves.

Main Results:

• The ADAPT-VQE approach successfully calculated ground and excited state potential curves for the hydrogen molecule.
• Explicitly correlated basis functions enabled high accuracy in the simulations.
• Chemical accuracy (<1.6 mHa) was achieved using relatively short quantum circuits.

Conclusions:

• The ADAPT algorithm, when combined with specific basis functions, is a viable approach for near-term quantum chemistry.
• This method demonstrates the potential of quantum computation for solving complex chemical problems.
• Short quantum circuits and high accuracy are achievable, paving the way for practical quantum applications in chemistry.