Emergent quantum computing technologies are widely expected to provide novel approaches in the simulation of quantum chemistry.Despite rapid improvements in the scale and fidelity of quantum computers, high resource requirements make the execution of quantum chemistry experiments challenging.Typical experiments are limited in the number of qubits used, incur a substantial shot cost, or require complex architecture-specific optimization and error mitigation techniques.In this paper, we propose a conceptually simple benchmarking approach involving the use of multi-ancilla quantum phase estimation.Our approach is restricted to very small chemical systems, and does not scale favorably beyond molecular systems that can be described with 2 qubits; however, this restriction allows us to generate circuits that scale quadratically in gate count with the number of qubits in the readout register.This enables the execution of quantum chemistry circuits that act on many qubits, while producing meaningful results with limited shot counts.We use this technique (with 200 shots per experiment) to calculate the ground state energy of molecular hydrogen to 50 bits of precision (8.9 × 10 −16 hartree) on a 56-qubit trapped-ion quantum computer, negating Trotter error.Including Trotter error, we obtain between 32 and 36 bits of precision (1.5 × 10 −10 and 6.0 × 10 −11 hartree respectively), vastly exceeding chemical accuracy (1.6×10 −3 hartree) against Full Configuration Interaction.We consider application of the approach to deeper circuits, and discuss potential as a benchmark task for near-term quantum devices.
This paper proposes a novel benchmarking approach using multi-ancilla Quantum Phase Estimation (QPE) on trapped-ion quantum computers to accurately estimate the ground state energy of small molecular systems like H₂. The authors demonstrate the practical execution of their method on a 56-qubit trapped-ion quantum computer, achieving a precision of 50 bits (8.9 × 10 -16 hartree) for the calculation while addressing Trotter error effectively. They discuss the limitations of their approach, such as scalability issues with larger molecular systems and challenges of error mitigation. Overall, the proposed method shows promise for benchmarking near-term quantum devices by allowing fixed-depth circuit designs suitable for exploratory quantum chemistry experiments.
This paper employs the following methods:
- Multi-ancilla Quantum Phase Estimation
- Quantum Phase Estimation (QPE)
- Trotterization
The following datasets were used in this research:
- Estimation of ground state energy for molecular hydrogen with 50 bits of precision
- Achieved a precision exceeding chemical accuracy (1.6×10 −3 hartree) against Full Configuration Interaction
The authors identified the following limitations:
- Limited scalability beyond small molecular systems (one or two qubits)
- Requires extensive error mitigation techniques for larger systems
- Practical limitations due to hardware noise and resource requirements
- Number of GPUs: None specified
- GPU Type: None specified
- Compute Requirements: 200 shots per experiment