87 citations · 288 across the 19 of their papers we have counts for
19 papers
Shorter width truncated Taylor series for Hamiltonian dynamics simulations
Michelle Wynne Sze, David Zsolt Manrique, David Muñoz Ramo +1
As established in the seminal work by Berry et al.[1], expanding the time evolution operator using truncated Taylor series (up to some order ) makes a good candidate for simulat…
Beyond asymptotic reasoning: the practicalities of a quantum ground state projector based on the wall-Chebyshev expansion
Maria-Andreea Filip, Nathan Fitzpatrick
We consider a quantum algorithm for ground-state preparation based on a Chebyshev series approximation to the wall function. In a classical setting, this approach is appealing as i…
The Quantum Paldus Transform: Efficient Circuits with Applications
Jędrzej Burkat, Nathan Fitzpatrick
We present the Quantum Paldus Transform: an efficient quantum algorithm for block-diagonalising fermionic, spin-free Hamiltonians in the second quantisation. Our algorithm implemen…
Hamiltonian dynamics simulation using linear combination of unitaries on an ion trap quantum computer
Michelle Wynne Sze, Yao Tang, Silas Dilkes +3
The linear combination of unitaries (LCU) method has proven to scale better than existing product formulas in simulating long time Hamiltonian dynamics. However, given the number o…
Realizing Quantum Kernel Models at Scale with Matrix Product State Simulation
Mekena Metcalf, Pablo Andrés-Martínez, Nathan Fitzpatrick
Data representation in quantum state space offers an alternative function space for machine learning tasks. However, benchmarking these algorithms at a practical scale has been lim…
Unification of Finite Symmetries in Simulation of Many-body Systems on Quantum Computers
Victor M. Bastidas, Nathan Fitzpatrick, K. J. Joven +5
Symmetry is fundamental in the description and simulation of quantum systems. Leveraging symmetries in classical simulations of many-body quantum systems can results in significant…
Quantum state preparation for multivariate functions
Matthias Rosenkranz, Eric Brunner, Gabriel Marin-Sanchez +5
A fundamental step of any quantum algorithm is the preparation of qubit registers in a suitable initial state. Often qubit registers represent a discretization of continuous variab…
Quantum Circuit Optimization with AlphaTensor
Francisco J. R. Ruiz, Tuomas Laakkonen, Johannes Bausch +10
A key challenge in realizing fault-tolerant quantum computers is circuit optimization. Focusing on the most expensive gates in fault-tolerant quantum computation (namely, the T gat…
Quantum Computed Green's Functions using a Cumulant Expansion of the Lanczos Method
Gabriel Greene-Diniz, David Zsolt Manrique, Kentaro Yamamoto +5
In this paper, we present a quantum computational method to calculate the many-body Green's function matrix in a spin orbital basis. We apply our approach to finite-sized fermionic…
Calculating the Single-Particle Many-body Green's Functions via the Quantum Singular Value Transform Algorithm
Alexis Ralli, Gabriel Greene-Diniz, David Muñoz Ramo +1
The Quantum Singular Value Transformation (QSVT) is a technique that provides a unified framework for describing many of the quantum algorithms discovered to date. We implement a n…
Simulating non-unitary dynamics using quantum signal processing with unitary block encoding
Hans Hon Sang Chan, David Muñoz Ramo, Nathan Fitzpatrick
We adapt a recent advance in resource-frugal quantum signal processing - the Quantum Eigenvalue Transform with Unitary matrices (QET-U) - to explore non-unitary imaginary time evol…
Non-unitary Trotter circuits for imaginary time evolution
Chiara Leadbeater, Nathan Fitzpatrick, David Muñoz Ramo +1
We propose an imaginary time equivalent of the well-established Pauli gadget primitive for Trotter-decomposed real time evolution, using mid-circuit measurements on a single ancill…
Variational Phase Estimation with Variational Fast Forwarding
Maria-Andreea Filip, David Muñoz Ramo, Nathan Fitzpatrick
Subspace diagonalisation methods have appeared recently as promising means to access the ground state and some excited states of molecular Hamiltonians by classically diagonalising…
A case study of variational quantum algorithms for a job shop scheduling problem
David Amaro, Matthias Rosenkranz, Nathan Fitzpatrick +2
Combinatorial optimization models a vast range of industrial processes aiming at improving their efficiency. In general, solving this type of problem exactly is computationally int…
Reducing Unitary Coupled Cluster Circuit Depth by Classical Stochastic Amplitude Pre-Screening
Maria-Andreea Filip, Nathan Fitzpatrick, David Muñoz Ramo +1
Unitary Coupled Cluster (UCC) approaches are an appealing route to utilising quantum hardware to perform quantum chemistry calculations, as quantum computers can in principle perfo…
Evaluating low-depth quantum algorithms for time evolution on fermion-boson systems
Nathan Fitzpatrick, Harriet Apel, David Muñoz Ramo
Simulating time evolution of quantum systems is one of the most promising applications of quantum computing and also appears as a subroutine in many applications such as Green's fu…
Molecular Excited State Calculations with Adaptive Wavefunctions on a Quantum Eigensolver Emulation: Reducing Circuit Depth and Separating Spin States
Hans Hon Sang Chan, Nathan Fitzpatrick, Javier Segarra-Marti +2
Ab initio electronic excited state calculations are necessary for the quantitative study of photochemical reactions, but their accurate computation on classical computers is plague…
Evaluating the noise resilience of variational quantum algorithms
Enrico Fontana, Nathan Fitzpatrick, David Muñoz Ramo +2
We simulate the effects of different types of noise in state preparation circuits of variational quantum algorithms. We first use a variational quantum eigensolver to find the grou…
Dynamical mean field theory algorithm and experiment on quantum computers
I. Rungger, N. Fitzpatrick, H. Chen +12
The developments of quantum computing algorithms and experiments for atomic scale simulations have largely focused on quantum chemistry for molecules, while their application in co…