Realizing Error Suppression in Partially Fault-Tolerant Quantum Simulations with IBM Quantum Computers

Using IBM’s superconducting quantum computer ibm boston, we show that partially fault-tolerant encoded quantum simulations of the Ising model in 1+1D and 2+1D outperform their unencoded counterparts in estimating local observables. To represent 42 logical qubits on the heavy-hex quantum processor, 21 blocks of the [[4, 2, 2]] Iceberg code and up to 136 physical qubits are used. This scheme preserves many of the benefits of error detection while avoiding the overhead typically required for a fully fault-tolerant logical gate set. We introduce Observable-Ranked Postselection, a selective-filtering technique based on syndrome correlations that recovers reliable results without the prohibitive shot loss of full syndrome postselection.

by Henry Froland, Dorota Grabowska, Sebastian Grieninger, Jeremy Hartse, Anne Lashbrook, Zhiyao Li, Ziyuan Li, Sarah Powell, Martin Savage, Xiaojun Yao, Nikita Zemlevskiy

Realizing Error Suppression in Partially Fault-Tolerant Quantum Simulations with IBM Quantum Computers

Randomized measurement protocols for lattice gauge theories

Randomized measurement protocols, including classical shadows, entanglement tomography, and randomized benchmarking are powerful techniques to estimate observables, perform state tomography, or extract the entanglement properties of quantum states. Quantum systems in nature are often tightly constrained by symmetries. This can be leveraged by the symmetry-conscious randomized measurement schemes, yielding clear advantages over symmetry-blind randomization such as reducing measurement costs, enabling symmetry-based error mitigation in experiments, allowing differentiated measurement of (lattice) gauge theory entanglement structure, and, potentially, the verification of topologically ordered states in existing and near-term experiments.

by Jacob Bringewatt, Jonathan Kunjummen, Niklas Mueller

IQuS Publications

Scalable quantum circuits are used to prepare the vacuum of the Schwinger model on 100 qubits of IBM's superconducting-qubit quantum computers

The vacuum of the lattice Schwinger model is prepared on up to 100 qubits of IBM’s Eagle-processor quantum computers. A new algorithm to prepare the ground state of a gapped translationally- invariant system on a quantum computer is presented, which we call Scalable Circuits ADAPT- VQE (SC-ADAPT-VQE). This algorithm uses the exponential decay of correlations between distant regions of the ground state, together with ADAPT-VQE, to construct quantum circuits for state preparation that can be scaled to arbitrarily large systems.

by Roland Farrell, Marc Illa, Anthony Ciavarella and Martin Savage

DOE Office of Science Highlight

A joint IQuS-QSC project

Scalable Circuits for Preparing Ground States on Digital Quantum Computers: The Schwinger Model Vacuum on 100 Qubits

IQuS Workshop 2023: Thermalization, from Cold Atoms to Hot Quantum Chromodynamics

Organizers: Alexey Gorshkov ( NIST, QuICS, JQI, U. of Maryland), Niklas Mueller (IQuS), Raju Venugopalan (BNL, C2QA) and Nicole Yunger Halpern (NIST, QuICS, JQI, IPST,U. of Maryland)

Administation: Katie Hennessey

Quantum computation and simulation promise rapid advances in understanding quantum thermalization, a challenging topic driving many fields. This workshop initiated an interdisciplinary conversation between researchers from high energy and nuclear physics, ultra-cold atomic and molecular gases, condensed matter physics and quantum information science. Its goal was to overcome challenges by exchanging ideas and concepts, as well as developing tools such as lattice gauge theory, aimed at phenomena surrounding quantum thermalization and open quantum systems, from a theoretical and experimental perspective. It covered interdisciplinary aspects of topics such as Eigenstate Thermalization, Universality, Entanglement Structure and Tomography, Hydrodynamization, and Quantum Thermodynamics.

Thermalization, from Cold Atoms to Hot Quantum Chromodynamics

Real-time Dynamics of the Schwinger Model as an Open Quantum System with Neural Density Operators

Ab-initio simulations of multiple heavy quarks propagating in a Quark-Gluon Plasma are computationally difficult to perform due to the large dimension of the space of density matrices. This work develops machine learning algorithms to overcome this difficulty by approximating exact quantum states with neural network parametrizations, specifically Neural Density Operators.The approach is applied to solve the Lindblad master equation in the 1+1D lattice Schwinger Model as an open quantum system. Neural Density Operators enable the study of in-medium dynamics on large lattice volumes, where multiple-string interactions and their effects on string-breaking and recombination phenomena can be studied. Thermal properties of the system at equilibrium can also be probed with these methods. Scaling of this approach with system size is studied, and numerical demonstrations on up to 32 spatial lattice sites and with up to 3 interacting strings are performed.

by Joshua Lin, Di Luo, Xiaojun Yao and Phiala Shanahan

Real-time Dynamics of the Schwinger Model as an Open Quantum System with Neural Density Operators

Classical and Quantum Computing of Shear Viscosity for 2+1D SU(2) Gauge Theory

We perform a nonperturbative calculation of the shear viscosity for 2+1-dimensional SU(2) gauge theory by using the lattice Hamiltonian formulation. The retarded Green’s function of the stress-energy tensor is calculated from real time evolution. We find the ratio of the shear viscosity and the entropy density eta/s is consistent with the holographic result 1/(4 pi) at several temperatures on a 4×4 hexagonal lattice with the local electric representation truncated at j_max=1/2. We also find the ratio of the spectral function and frequency rho^(xy)(omega)/omega exhibits a peak structure when the frequency is small. We develop a quantum computing method to calculate the Green’s function and analyze systematics of the calculation. We test our quantum circuit on both the Quantinuum emulator and the IBM simulator for a small lattice and obtain results consistent with the classical computing ones.

by Francesco Turro, Anthony Ciavarella and Xiaojun Yao

Editors Highlight

Classical and Quantum Computing of Shear Viscosity for 2+1D SU(2) Gauge Theory

Quantum Magic and Multi-Partite Entanglement in the Structure of Nuclei

Motivated by the Gottesman-Knill theorem, we present a detailed study of the quantum complexity of p-shell and sd-shell nuclei. Significant multi-nucleon entanglement is found in the sd-shell, dominated by proton neutron configurations, along with significant measures of magic. This is evident not only for the deformed states, but also for nuclei on the path to instability via regions of shape coexistence and level inversion. These results indicate that quantum-computing resources will accelerate precision simulations of such nuclei and beyond.

by Florian Brokemeier, Momme Hengstenberg, James Keeble, Caroline Robin, Federico Rocco, Martin Savage

Quantum Magic and Multi-Partite Entanglement in the Structure of Nuclei

IQuS Workshop 2024: Entanglement in Many-Body Systems: From Nuclei to Quantum Computers and Back

Organizers: Mari Carmen Banuls (Max Planck Institute for Quantum Optics, Munich, Germany), Susan Coppersmith (University of New South Wales, Sydney, Australia), Calvin Johnson (San Diego State University, California, USA) and Caroline Robin (Bielefeld University, Germany).

Administation: Katie Hennessey

This workshop centered around the topic of entanglement in many-body systems relevant for and connected to NP. The goal was to advance exchanges of ideas and techniques between NP and other fields of many-body physics such as condensed matter, quantum chemistry or quantum field theories. The knowledge acquired in these fields can guide progress in the development of entanglement-driven methods for classical and quantum simulations of nuclei, and in the identification of experiments probing entanglement in nuclear systems. Vice versa, specificities of many-body NP techniques can potentially be useful for other fields, and QIS in general. The workshop will explore these different aspects.

Entanglement in Many-Body Systems: From Nuclei to Quantum Computers and Back

IonQ-IQuS Co-Design of Double-Beta Decay

We present results from co-designed quantum simulations of the neutrinoless double-beta decay of a two-hadron nucleus in 1+1D quantum chromodynamics using IonQ’s Forte-generation trapped-ion quantum computers. Two flavors of dynamical quarks and leptons are distributed across two lattice sites and mapped to 32 qubits. Lepton-number violation is induced by a neutrino Majorana mass. This was made possible by co-designing the state preparation and time evolution quantum circuits to maximally utilize the all-to-all connectivity and native gate-set available on IonQ’s quantum computers. Quantum circuit compilation techniques and symmetry-aware error-mitigation methods, tailored to neutrinoless decays, allow accurate results to be extracted from quantum circuits with up to 470 two-qubit gates using Forte Enterprise.

A joint IQuS-IonQ Co-design project.

Nature Communication, 17, Article number: 1826 (2026)

Pathfinding Quantum Simulations of Neutrinoless Double-Beta Decay

The Utility of Sparse Error Detection in Quantum Simulations

We examine the utility of sparse error detection for simulating lattice gauge theories using quantum computers. In particular, we study the time evolution of the lattice Schwinger model embedded into the Iceberg code family, [[N+2, N, 2]], as well as the Hypercube code family, [[2^N, N, 2]]. Noisy classical simulations with realistic near-term error rates, infrequent syndrome measurements and physics-aware postselection are found to improve observable estimation. Under realistic noise rates for near-term quantum computers, this work finds that sparse error detection in quantum simulations has the potential to improve accuracy of observable estimation. These findings suggest that incorporating minimal implementations of fault tolerance in the near-term will enhance the performance of quantum simulations in nuclear physics and high-energy physics.

by Henry Froland, Dorota Grabowska, Sebastian Grieninger, Jeremy Hartse, Anne Lashbrook, Zhiyao Li, Ziyuan Li, Sarah Powell, Martin Savage, Xiaojun Yao, Nikita Zemlevskiy

The Utility of Sparse Error Detection in Quantum Simulations

InQubator for Quantum Simulation

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Realizing Error Suppression in Partially Fault-Tolerant Quantum Simulations with IBM Quantum Computers

Randomized measurement protocols for lattice gauge theories

Scalable quantum circuits are used to prepare the vacuum of the Schwinger model on 100 qubits of IBM's superconducting-qubit quantum computers

IQuS Workshop 2023: Thermalization, from Cold Atoms to Hot Quantum Chromodynamics

Real-time Dynamics of the Schwinger Model as an Open Quantum System with Neural Density Operators

Classical and Quantum Computing of Shear Viscosity for 2+1D SU(2) Gauge Theory

Quantum Magic and Multi-Partite Entanglement in the Structure of Nuclei

IQuS Workshop 2024: Entanglement in Many-Body Systems: From Nuclei to Quantum Computers and Back

IonQ-IQuS Co-Design of Double-Beta Decay

The Utility of Sparse Error Detection in Quantum Simulations

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