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Determining eigenstates and thermal states on a quantum computer using quantum imaginary time evolution
The quantum imaginary time evolution and Lanczos algorithms offer a resource-efficient way to compute ground or excited states of target Hamiltonians on quantum computers, and offers promise for quantum simulation on near-term noisy devices.
Qubitization of Arbitrary Basis Quantum Chemistry Leveraging Sparsity and Low Rank Factorization
This work shows that one can achieve similar scaling even for arbitrary basis sets by using qubitized quantum walks in a fashion that takes advantage of structure in the Coulomb operator, either by directly exploiting sparseness, or via a low rank tensor factorization.
Recent developments in the PySCF program package.
The design and philosophy behind PySCF, a Python-based general-purpose electronic structure platform that supports first-principles simulations of molecules and solids as well as accelerates the development of new methodology and complex computational workflows, is explained.
Towards the solution of the many-electron problem in real materials: equation of state of the hydrogen chain with state-of-the-art many-body methods
We present numerical results for the equation of state of an infinite chain of hydrogen atoms. A variety of modern many-body methods are employed, with exhaustive cross-checks and validation.…
Low rank representations for quantum simulation of electronic structure
The gate complexity of performing Hamiltonian and unitary Coupled Cluster Trotter steps makes simulation based on such primitives challenging, but this work substantially reduces the gate complexity through a two-step low-rank factorization of the Hamiltonians and cluster operator, accompanied by truncation of small terms.
Quantum Computation of Finite-Temperature Static and Dynamical Properties of Spin Systems Using Quantum Imaginary Time Evolution
- Shi-Ning Sun, M. Motta, Ruslan N. Tazhigulov, A. T. Tan, G. Chan, A. Minnich
- Physics, Computer SciencePRX Quantum
- 8 September 2020
This work demonstrates that the ansatz-independent QITE algorithm is capable of computing diverse finite-temperature observables on near-term quantum devices.
Quantum Imaginary Time Evolution, Quantum Lanczos, and Quantum Thermal Averaging
The quantum imaginary time evolution and quantum Lanczos algorithms are described, analogs of classical algorithms for ground (and excited) states, but with exponentially reduced space and time requirements per iteration, and without deep circuits, ancillae, or high-dimensional non-linear optimization.
Ab initio computations of molecular systems by the auxiliary‐field quantum Monte Carlo method
The auxiliary‐field quantum Monte Carlo (AFQMC) method provides a computational framework for solving the time‐independent Schrödinger equation in atoms, molecules, solids, and a variety of model…
Quantum Filter Diagonalization with Compressed Double-Factorized Hamiltonians
We demonstrate a method that merges the quantum filter diagonalization (QFD) approach for hybrid quantum/classical solution of the time-independent electronic Schrödinger equation with a low-rank…
Experimental Realization of a Measurement-Induced Entanglement Phase Transition on a Superconducting Quantum Processor
entanglement of h S α ( T ) i − h S α ( T = 0) i against T , for diﬀering system sizes L , and subsystem sizes | A | on which tomography is performed. Quantum state tomography for | A | ≤ 2 was…