Quantum Systems for Analog Simulation

For those tracking progress in Quantum… As my colleague Hartmut Neven has predicted, real-world applications possible only on quantum computers are much closer than people think – as near as five years, even though fully error corrected quantum computers may be further away.  Recently, my colleagues on our Quantum AI team at Google Research took another important step on that path with a new set of results we published last week in Nature that share a promising new approach to applications on today’s quantum computers. Our analog-digital quantum simulator using super-conducting qubits shows performance beyond the reach of classical simulations in cross-entropy benchmarking experiments. Simulations with the level of experimental fidelity in this simulator would require more than a million years on a Frontier supercomputer. The simulator brings together digital’s flexibility and control with the analog’s speed – and provides a path towards applications that cannot be accomplished on a classical computer. Along the way, my colleagues also made a scientific discovery – they observed the breakdown of a well-known prediction in non-equilibrium physics, the Kibble-Zurek mechanism - an important result in our understanding of magnetism, and also useful in various kinds of quantum simulations. Congratulations to Trond Andersen, Nikita Astrakhantsev, and the rest of the team on this exciting step – much more to come! You can read the Nature paper here: https://lnkd.in/gg2En5qe 

The Schrödinger Equation Gets Practical: Quantum Algorithm Speeds Up Real-World Simulations Quantum computing has taken a major leap forward with a new algorithm designed to simulate coupled harmonic oscillators, systems that model everything from molecular vibrations to bridges and neural networks. By reformulating the dynamics of these oscillators into the Schrödinger equation and applying Hamiltonian simulation methods, researchers have shown that complex physical systems can be simulated exponentially faster on a quantum computer than with traditional algorithms. This breakthrough demonstrates not only a practical use of the Schrödinger equation but also the deep connection between quantum dynamics and classical mechanics. The study introduces two powerful quantum algorithms that reduce the required resources to only about log(N) qubits for N oscillators, compared to the massive computational demands of classical methods. This exponential speedup could transform fields such as engineering, chemistry, neuroscience, and material science, where coupled oscillators serve as the backbone of real-world modeling. By bridging theory and application, this research underscores how quantum computing is redefining problem-solving in physics and beyond. With proven exponential advantages and the ability to simulate systems once thought computationally impossible, this quantum algorithm marks a milestone in quantum simulation, Hamiltonian dynamics, and real-world physics applications. The findings point toward a future where quantum computers can accelerate scientific discovery, optimize engineering designs, and even open new frontiers in AI and computational neuroscience. #QuantumComputing #SchrodingerEquation #HamiltonianSimulation #QuantumAlgorithm #CoupledOscillators #QuantumPhysics #ComputationalScience #Neuroscience #Chemistry #Engineering

In our new paper just posted on arXiv, we describe demonstration of a cavity QED system with up to ~10 individually controlled color centers (silicon vacancies) coupled to 2 modes of a high quality silicon carbide (SiC) resonator. Our work shows that this semiconductor, chip-scale platform has potential to implement quantum simulators. Apart from being chip-scale, this system offers some advantages relative to atomic cavity QED, and enables studies of new regimes and Hamitonians in quantum optics: 1. In-situ optical nonlinearity: We use optical (Kerr) nonlinearity of SiC resonator to realize a parametric drive term, where cavity QED system is driven directly by the spontaneous photon pair generation inside of it. 2. Spatial (phase) and spectral disorder of atoms (color centers): is easier to achieve, and we use it to demonstrate suppression of photon correlations and the emergence of steady-state chirality resulting from symmetry breaking. The work was led by Daniil Lukin and Dominic Catanzaro from Vučković Lab at Stanford, Bennet Windt and Miguel Bello from the Max Planck Institute of Quantum Optics, in collaboration with many current and former members of my group: Melissa Guidry, Eran Lustig, Souvik Biswas, Giovanni Scuri, Kien Le, and Joshua Yang. Silicon carbide was grown by our collaborators Misagh Ghezellou and Jawad Ul Hassan at the Linkoping University in Sweden, and e-beam irradiation to generate color centers was done by Hiroshi Abe and Takeshi OHSHIMA at the National Institutes for Quantum Science and Technology in Japan. The work of the Vučković Lab at Stanford was supported by the Vannevar Bush Faculty Fellowship from the US Department of Defense Basic Research Office (Under the Office of the Undersecretary of Defense for Research & Engineering) .

⚛️ Harnessing Intrinsic Noise for Quantum Simulation of Open Quantum Systems 📑 Simulating open quantum systems on quantum computers presents a fundamental challenge: open quantum dynamics are intrinsically nonunitary, whereas quantum computers operate through unitary evolution. Conventional approaches overcome this mismatch by encoding nonunitary processes into unitary circuits, but such methods incur substantial overhead in both qubits and gates. Here, we propose an alternative perspective. Quantum processors are themselves open systems, inherently subject to noise. Instead of correcting all errors and then encoding nonunitary dynamics with unitary logical qubits and gates, we show how noise can be harnessed as a computational resource. We develop a noise-assisted quantum algorithm that selectively preserves physical noise to emulate nonunitary channels, enabling efficient simulation of open quantum dynamics with minimal qubit requirements. Our approach applies both to noisy intermediate-scale quantum (NISQ) devices and future fault-tolerant architectures. By leveraging intrinsic noise, this method circumvents the need to encode nonunitary dynamics into unitary gates and relaxes fidelity requirements on physical qubits, thereby reducing the overhead of quantum error correction. This framework reframes noise from a limitation into a resource, opening new directions for practical quantum simulation of open systems ℹ️ Dambal et al - 2025

"STRING BREAKING" AND FLUX TUBE DYNAMICS IN (2+1) DIMENSIONAL QUANTUM SYSTEMS Using a programmable neutral-atom quantum simulator, research team at the University of Innsbruck, Harvard, and QuEra Computing evaluated the string breaking in a (2+1)D lattice gauge theory (LGT), a tabletop analog of quark confinement in quantum chromodynamics (QCD). In QCD, a significant amount of energy is concentrated within the gluon flux tube that confines a quark–antiquark pair. As a quark–antiquark pair is pulled apart, the energy confined within the gluonic flux string connecting them increases linearly with separation. This stored energy eventually becomes sufficient to nucleate new quark–antiquark pairs from the vacuum, resulting in the effective fragmentation of the original flux tube, string, into the shorter segments. In high-energy particle collisions, this mechanism results in the indirect observation of quarks through the formation of "jets", streams of secondary particles generated by the sequential breaking of the color field. Analogous phenomena are widespread across gauge theories that mirror the structure of QCD, particularly in lattice formulations governed by local gauge symmetry constraints. These models capture confinement and string-breaking dynamics through discrete spacetime representations, offering a powerful framework to investigate nonperturbative field behavior. Despite their ubiquity, capturing LGTs real-time evolution through simulation remains a profound computational challenge. Utilizing QuEra’s Aquila neutral-atom quantum simulator and programmable Rydberg atom array, researchers configured several rubidium atoms into a kagome-geometry optical-tweezer array, effectively implementing a synthetic LGT that mirrors the confinement dynamics of strong nuclear force in QCD. By finely tuning the laser control parameters, the team engineered and dynamically extended flux-tube-like structures between synthetic charges. As the simulated energy scale approached, the experiment captured both static confinement signatures and nanosecond-scale, real-time evolution of the string rupture, pushing beyond the reach of classical computational methods. In contrast to efforts employing digital quantum processors, these experiments revealed that string breaking is a genuine many-body phenomenon, which arises from physical realization of a confining U(1) LGT with dynamical matter, mapped directly onto the system’s Hamiltonian. Unlike prior implementations limited to (1+1)D configurations, this approach facilitates the construction of an equilibrium phase diagram, characterizing regimes of broken and unbroken strings in (2+1)D space-time, achieved through finely tunable local control and quasi-adiabatic state preparation and controlled quench of local parameters on preconfigured flux tubes, providing access to the real-time dynamics of confinement and string breaking with the fine spatio-temporal resolution. # https://lnkd.in/eKgfAFPb

🧮 From quantum computing to materials design, the ability to simulate open quantum systems is key — but doing it efficiently and correctly has remained a major challenge. 🎓 Exciting work from the Virginia Tech Department of Mathematics! The outstanding collaborative team of Professors Daniel Appelö and Yingda Cheng have published “Kraus is king: High-order completely positive and trace-preserving (CPTP) low-rank method for the Lindblad master equation” in the Journal of Computational Physics. https://lnkd.in/eWZkiSMz 💡 Their paper tackles one of the hardest problems in quantum computation and open-system simulation — how to design algorithms that are both efficient and physically faithful. ⚙️ They introduce a new class of high-order, low-rank integrators that preserve the essential structure of quantum mechanics (complete positivity and trace preservation) while dramatically reducing computational cost. A particularly elegant result shows that truncated SVD operations themselves are completely positive maps, enabling accurate and stable low-rank quantum simulations. 🚀 This work exemplifies the cutting-edge computational and mathematical research happening in Virginia Tech’s College of Science — connecting numerical analysis, quantum physics, and high-performance computing to advance the next generation of quantum technologies.

𝗔𝗱𝘃𝗮𝗻𝗰𝗲𝗺𝗲𝗻𝘁𝘀 𝗶𝗻 𝗾𝘂𝗮𝗻𝘁𝘂𝗺 𝘀𝗶𝗺𝘂𝗹𝗮𝘁𝗶𝗼𝗻𝘀 𝗮𝗿𝗲 𝗵𝗲𝗿𝗲! While many quantum hardware platforms aren't yet fully fault-tolerant, they can still function as analogue quantum simulators to address complex many-body problems. This paper explores this potential. 🚀🔬 🔍 𝗞𝗲𝘆 𝗛𝗶𝗴𝗵𝗹𝗶𝗴𝗵𝘁𝘀: 𝗘𝗿𝗿𝗼𝗿 𝗦𝘁𝗮𝗯𝗶𝗹𝗶𝘁𝘆: The paper introduces a novel, system-size independent notion of stability against extensive errors. This has been proven for Gaussian fermion models and a specific class of spin systems, indicating these models remain stable even with errors. 📊🛡️ 𝗖𝗿𝗶𝘁𝗶𝗰𝗮𝗹 𝗠𝗼𝗱𝗲𝗹 𝗦𝘁𝗮𝗯𝗶𝗹𝗶𝘁𝘆: Remarkably, the analysis shows that critical models with long-range correlations also exhibit stability, suggesting robustness in systems with extensive interactions. 🌐💡 𝗤𝘂𝗮𝗻𝘁𝘂𝗺 𝗔𝗱𝘃𝗮𝗻𝘁𝗮𝗴𝗲 𝗣𝗼𝘁𝗲𝗻𝘁𝗶𝗮𝗹: The authors examine how this stability might lead to a quantum advantage for computing the thermodynamic limit of many-body models, even with a constant error rate and without explicit error correction. This could enable practical applications of quantum simulators in solving complex physical problems. 🧩🔗 Explore the details of this transformative research and its potential to shape the future of quantum simulations. 🌐✨ #QuantumComputing #QuantumSimulators #ManyBodyProblems #ResearchInnovation #QuantumAdvantage

By blending digital control with analog simulations, scientists have created a powerful new quantum simulator that pushes beyond traditional limitations. This hybrid system allows precise manipulation of quantum states while naturally modeling real-world physics, enabling breakthroughs in fields like magnetism, superconductors, and even astrophysics. Physicists working in Google’s laboratory have developed a new type of digital-analog quantum simulator, capable of studying complex physical processes with unprecedented precision and adaptability. Consider the simple act of pouring cold milk into hot coffee — how does it spread and mix? Even the most advanced supercomputers struggle to model this process with high accuracy because the underlying quantum mechanics are incredibly complex. In 1982, Nobel Prize-winning physicist Richard Feynman proposed an alternative: instead of using classical computers, why not build quantum computers that can directly simulate quantum physical processes? Now, with rapid advancements in quantum computing, Feynman’s vision is closer than ever to becoming reality. https://lnkd.in/gjNP8q3e #universal #simulation #3Ddigitaltwin #Feynman #quantum

D-Wave researchers have published findings in Science demonstrating that their quantum annealing processors can simulate quantum spin glass dynamics more efficiently than leading classical methods. The study shows their quantum computers can perform simulations in minutes that would reportedly take classical supercomputers millions of years, marking a significant step toward practical quantum advantage in scientific applications. #QuantumComputing #DWave #QuantumSimulation #SpinGlass #ComputationalPhysics #QuantumSupremecy