Chemically aware unitary coupled cluster with ab initio calculations on an ion trap quantum computer: A refrigerant chemicals’ application

Abstract

Circuit depth reduction is of critical importance for quantum chemistry simulations on current and near term quantum computers. This issue is tackled by introducing a chemically aware strategy for the unitary coupled cluster ansatz. The objective is to use the chemical description of a system to aid in the synthesis of a quantum circuit. We combine this approach with two flavors of symmetry verification for the reduction of experimental noise. These methods enable the use of Quantinuum’s System Model H1 ion trap quantum computer for a 6-qubit quantum subspace expansion calculation. We present (i) calculations to obtain methane’s optical spectra; (ii) an atmospheric gas reaction simulation involving [CH3⋅—H—OH]‡. Using our chemically aware unitary coupled cluster state-preparation strategy in tandem with state of the art symmetry verification methods, we improve device yield for CH4 at 6 qubits. This is demonstrated by a 90% improvement in two-qubit gate count and a reduction in relative error to 0.2% for electronic energy calculated on System Model H1.

Quantum hardware calculations of the activation and dissociation of nitrogen on iron clusters and surfaces

“…For the state preparation, we applied the Adaptive Derivative-Assembled Pseudo-Trotter (ADAPT 15 ) approach, which uses the Unitary Coupled Cluster Singles Doubles formalism (UCCSD) excitation pool and the ‘Chemically Aware’ 54 circuit synthesis method. The Jordan–Wigner transformation was used.…”

Implementation of the Projective Quantum Eigensolver on a Quantum Computer

“…In the literature, the closest reference points are VQE computations, as hardware results on PQE have not yet been reported. Some papers have reported VQE ground-state energies or properties. ,,− Other studies have used VQE as an ingredient of methods to compute excited-state energies and properties, ,,,,,,,,− linear response properties, , molecular dynamics, and vibrational eigenstates, , while yet more studies have used VQE as an active space solver for a dynamical correlation or embedding method. ,− Of particular interest to this paper are those VQE computations that report the effectiveness of different error mitigation schemes, ,,,,,,,,,,,,,,,, or that are performed on IBM devices. ,,,− ,,…”

“… 17 , 41 , 54 − 93 Other studies have used VQE as an ingredient of methods to compute excited-state energies and properties, 41 , 58 , 60 , 69 , 70 , 76 , 77 , 87 , 94 − 96 linear response properties, 57 , 97 molecular dynamics, 98 and vibrational eigenstates, 99 , 100 while yet more studies have used VQE as an active space solver for a dynamical correlation or embedding method. 96 , 101 − 108 Of particular interest to this paper are those VQE computations that report the effectiveness of different error mitigation schemes, 56 , 59 , 60 , 63 , 64 , 69 , 73 , 75 , 79 , 82 , 83 , 85 , 88 , 93 , 94 , 103 , 105 or that are performed on IBM devices. 41 , 54 , 55 , 58 − 60 , 62 , 65 , 67 , 69 , 73 , 74 , 76 , 78 , 79 , 82 , 85 , 87 − 89 , 92 , 93 , 95 , 97 − 105 , …”