Simulated quantum computation of molecular energies

Area of Science:

• Quantum computing
• Computational chemistry
• Quantum algorithms

Background:

• Classical computers face exponential scaling challenges for atomic and molecular energy calculations.
• Quantum algorithms offer a potential solution with polynomial scaling.

Purpose of the Study:

• To demonstrate the applicability of quantum algorithms to chemical problems.
• To reduce the quantum bit requirements for molecular energy calculations.

Main Methods:

• Utilized a recursive phase-estimation algorithm on a quantum computer simulator.
• Employed an adiabatic method for approximate ground-state wave function preparation.
• Mapped molecular wave functions to quantum bits.

Main Results:

• Successfully calculated ground-state energies for water and lithium hydride molecules.
• Reduced quantum bit requirements for the readout register from 20 to 4.
• Demonstrated linear scaling of quantum bits with basis functions and polynomial scaling of gates with quantum bits.

Conclusions:

• Quantum algorithms are viable for chemical energy calculations with modest quantum bit counts.
• The recursive phase-estimation algorithm significantly enhances efficiency.
• Adiabatic methods provide effective ground-state wave function preparation.