107 citations · 306 across the 14 of their papers we have counts for
15 papers
Single-Particle Spectral Estimation
Adrian Chapman, Charles Derby, Steven T. Flammia +3
We study Hamiltonian learning in a novel setting, where we are promised a physical structure that is obfuscated by a global unitary. In particular, we consider the task of learning…
Programmable digital quantum simulation of 2D Fermi-Hubbard dynamics using 72 superconducting qubits
Faisal Alam, Jan Lukas Bosse, Ieva Čepaitė +41
Simulating the time-dynamics of quantum many-body systems was the original use of quantum computers proposed by Feynman, motivated by the critical role of quantum interactions betw…
Fermionic dynamics on a trapped-ion quantum computer beyond exact classical simulation
Faisal Alam, Jan Lukas Bosse, Ieva Čepaitė +37
Simulation of the time-dynamics of fermionic many-body systems has long been predicted to be one of the key applications of quantum computers. Such simulations -- for which classic…
Optimizing fermionic encodings for both Hamiltonian and hardware
Riley W. Chien, Joel Klassen
In this work we present a method for generating a fermionic encoding tailored to a set of target fermionic operators and to a target hardware connectivity. Our method uses brute fo…
Towards near-term quantum simulation of materials
Laura Clinton, Toby Cubitt, Brian Flynn +6
Simulation of materials is one of the most promising applications of quantum computers. On near-term hardware the crucial constraint on these simulations is circuit depth. Many qua…
Phase Estimation of Local Hamiltonians on NISQ Hardware
Laura Clinton, Johannes Bausch, Joel Klassen +1
In this work we investigate a binned version of Quantum Phase Estimation (QPE) set out by [Somma 2019] and known as the Quantum Eigenvalue Estimation Problem (QEEP). Specifically,…
A Compact Fermion to Qubit Mapping Part 2: Alternative Lattice Geometries
Charles Derby, Joel Klassen
In recent work [arXiv:2003.06939v2] a novel fermion to qubit mapping -- called the compact encoding -- was introduced which outperforms all previous local mappings in both the qubi…
Termwise versus globally stoquastic local Hamiltonians: questions of complexity and sign-curing
Marios Ioannou, Stephen Piddock, Milad Marvian +2
We elucidate the distinction between global and termwise stoquasticity for local Hamiltonians and prove several complexity results. We show that the stoquastic local Hamiltonian pr…
Mitigating Errors in Local Fermionic Encodings
Johannes Bausch, Toby Cubitt, Charles Derby +1
Quantum simulations of fermionic many-body systems crucially rely on mappings from indistinguishable fermions to distinguishable qubits. The non-local structure of fermionic Fock s…
A Compact Fermion to Qubit Mapping
Charles Derby, Joel Klassen
Mappings between fermions and qubits are valuable constructions in physics. To date only a handful exist. In addition to revealing dualities between fermionic and spin systems, suc…
Hardness and Ease of Curing the Sign Problem for Two-Local Qubit Hamiltonians
Joel Klassen, Milad Marvian, Stephen Piddock +3
We examine the problem of determining whether a multi-qubit two-local Hamiltonian can be made stoquastic by single-qubit unitary transformations. We prove that when such a Hamilton…
Two-local qubit Hamiltonians: when are they stoquastic?
Joel Klassen, Barbara M. Terhal
We examine the problem of determining if a 2-local Hamiltonian is stoquastic by local basis changes. We analyze this problem for two-qubit Hamiltonians, presenting some basic tools…
Quantum state tomography via reduced density matrices
Tao Xin, Dawei Lu, Joel Klassen +7
Quantum state tomography via local measurements is an efficient tool for characterizing quantum states. However it requires that the original global state be uniquely determined (U…
Topological degeneracy (Majorana zero-mode) and 1+1D fermionic topological order in a magnetic chain on superconductor via spontaneous Z2 symmetry breaking
Joel Klassen, Xiao-Gang Wen
We study a chain of ferromagnetic nano-particles or ferromagnetic molecule/atoms on a substrate of fully gapped superconductors. We find that under quite realistic conditions, the…
Universal Entanglers for Bosonic and Fermionic Systems
Joel Klassen, Jianxin Chen, Bei Zeng
A universal entangler (UE) is a unitary operation which maps all pure product states to entangled states. It is known that for a bipartite system of particles with a Hilbert…