Molecular VQE Control Through Selective Two-Qubit Gates
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Solution Overview
Problem
Conventional variational quantum eigensolver (VQE) techniques for quantum chemical computation require extensive computation time due to deep circuit lengths and increased parameters, leading to inefficiencies in calculating energy expectation values for molecular ground states.
Innovation Solution
A quantum computation method that selectively applies two-qubit gates generating superposition states only to qubit pairs with a high effect on energy expectation value reduction, optimizing the quantum circuit by reducing unnecessary gate operations and parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional VQE techniques are used with deep circuit lengths and increased parameters, then computation accuracy is maintained, but computation time increases significantly
Solution Approach 1:
The patent extracts and removes unnecessary two-qubit gates from the quantum circuit by identifying qubit pairs that have minimal effect on the energy expectation value. This selective removal maintains computation accuracy while significantly reducing circuit depth and computation time
Solution Approach 2:
The patent applies different treatment to different qubit pairs based on their local importance. Qubit pairs are evaluated individually using importance metrics, and only those with high importance retain two-qubit gates. This localized optimization maintains accuracy where needed while reducing operations where unnecessary
2Measurement precision
If two-qubit gates are applied to all qubit pairs, then computation accuracy is maintained, but device complexity and number of parameters increase
Solution Approach 1:
The patent changes the parameter configuration by selectively setting parameters (two-qubit gate operations) to zero or removing them for low-importance qubit pairs. This parameter optimization reduces the effective number of parameters and circuit complexity while maintaining accuracy through importance-based selection
3Measurement precision
If extensive two-qubit gate operations are performed, then accurate energy expectation value is obtained, but productivity decreases
Solution Approach 1:
The patent applies partial action by performing two-qubit gate operations only on a subset of qubit pairs that are identified as having high importance. This partial application of operations maintains the necessary accuracy for energy expectation value calculation while significantly improving computation efficiency by avoiding unnecessary operations on low-importance qubit pairs
Data Source
AI summary
An information processing apparatus creates qubit pairs, each being formed by combining first and second qubits. A first qubit corresponds to a first orbital on which an electron is present in an initial arrangement. A second qubit corresponds to a second orbital on which no electron is present in the initial arrangement. The apparatus generates a quantum circuit that applies two-qubit gates to at least some of the qubit pairs. Each two-qubit gate generates, based on the value of a parameter, a superposition state of a first state in which the states of the first and second qubits are not switched and a second state in which these states are switched. The apparatus acquires an energy expectation value in the ground state of the molecule by causing a quantum computer to iteratively execute the quantum circuit.