Computing ground state properties with early fault-tolerant quantum computers

R Zhang, G Wang, P Johnson - Quantum, 2022 - quantum-journal.org
Significant effort in applied quantum computing has been devoted to the problem of ground
state energy estimation for molecules and materials. Yet, for many applications of practical …

Entanglement in highly symmetric multipartite quantum states

A Burchardt, J Czartowski, K Życzkowski - Physical Review A, 2021 - APS
A construction of genuinely entangled multipartite quantum states based on the group theory
is presented. Analyzed states resemble the Dicke states, whereas the interactions occur only …

Optimizing the depth of variational quantum algorithms is strongly QCMA-hard to approximate

L Bittel, S Gharibian, M Kliesch - arxiv preprint arxiv:2211.12519, 2022 - arxiv.org
Variational Quantum Algorithms (VQAs), such as the Quantum Approximate Optimization
Algorithm (QAOA) of [Farhi, Goldstone, Gutmann, 2014], have seen intense study towards …

Computational complexity of the ground state energy density problem

JD Watson, TS Cubitt - Proceedings of the 54th Annual ACM SIGACT …, 2022 - dl.acm.org
We study the complexity of finding the ground state energy density of a local Hamiltonian on
a lattice in the thermodynamic limit of infinite lattice size. We formulate this rigorously as a …

Hamiltonian complexity in the thermodynamic limit

D Aharonov, S Irani - Proceedings of the 54th Annual ACM SIGACT …, 2022 - dl.acm.org
Despite immense progress in quantum Hamiltonian complexity in the past decade, little is
known about the computational complexity of quantum physics at the thermodynamic limit. In …

Gibbs Sampling gives Quantum Advantage at Constant Temperatures with O (1)-Local Hamiltonians

J Rajakumar, JD Watson - arxiv preprint arxiv:2408.01516, 2024 - arxiv.org
Sampling from Gibbs states--states corresponding to system in thermal equilibrium--has
recently been shown to be a task for which quantum computers are expected to achieve …

Guest Column: The 7 faces of quantum NP

S Gharibian - ACM SIGACT News, 2024 - dl.acm.org
When it comes to NP, its natural definition, its wide applicability across scientific disciplines,
and its timeless relevance, the writing is on the wall: There can be only one. Quantum NP …

The complexity of approximating critical points of quantum phase transitions

JD Watson, J Bausch - arxiv preprint arxiv:2105.13350, 2021 - arxiv.org
Phase diagrams chart material properties with respect to one or more external or internal
parameters such as pressure or magnetisation; as such, they play a fundamental role in …

Hardness of approximation for ground state problems

S Gharibian, C Hecht - arxiv preprint arxiv:2411.04874, 2024 - arxiv.org
After nearly two decades of research, the question of a quantum PCP theorem for quantum
Constraint Satisfaction Problems (CSPs) remains wide open. As a result, proving QMA …

Quantum space, ground space traversal, and how to embed multi-prover interactive proofs into unentanglement

S Gharibian, D Rudolph - arxiv preprint arxiv:2206.05243, 2022 - arxiv.org
Savitch's theorem states that NPSPACE computations can be simulated in PSPACE. We
initiate the study of a quantum analogue of NPSPACE, denoted Streaming-QCMASPACE …