Trinity College Dublin’s quantum physicists and IBM Dublin have simulated super diffusion on a quantum computer, a first step in complex quantum transport calculations. The work is part of the TCD-IBM predoctoral scholarship programme, where IBM hires PhD students co-supervised at Trinity. The quantum computer used, located in IBM’s New York lab, consists of 27 superconducting qubits. The team simulated spin chains, systems of connected magnets used to understand magnetism. The research was led by Trinity’s Professor John Goold, Director of the Trinity Quantum Alliance. The Alliance includes IBM, Microsoft, Algorithmiq, Horizon and Moodys Analytics.
Quantum Physicists Simulate Super Diffusion on Quantum Computer
A team of quantum physicists from Trinity College Dublin, in collaboration with IBM Dublin, have successfully simulated super diffusion in a system of interacting quantum particles on a quantum computer. This marks a significant step in performing complex quantum transport calculations on quantum hardware. As the hardware continues to improve, this work is expected to provide new insights into condensed matter physics and materials science.
The quantum computer used in this study, located in IBM’s lab in New York, consists of 27 superconducting qubits, which are the fundamental building blocks of quantum logic. The computer was programmed remotely from Dublin. This work is one of the first outputs of the TCD-IBM predoctoral scholarship program, which hires PhD students as employees while being co-supervised at Trinity. The findings were recently published in the Nature journal NPJ Quantum Information.
Quantum Computing: A Promising Technology
Quantum computing is currently one of the most promising technologies, with potential commercial applications expected to emerge in the next decade. Beyond commercial applications, quantum computers can help answer fundamental questions in physics. The team at Trinity and IBM Dublin tackled one such question concerning quantum simulation.
Simulating the dynamics of a complex quantum system with many interacting constituents is a formidable challenge for conventional computers. As the number of qubits in a system increases, the number of coefficients required to describe the system’s state also increases exponentially. For instance, a system with 300 qubits would require more coefficients than there are atoms in the observable universe. Quantum computers, however, can naturally exploit their wave function to circumvent the need for exponential classical resources for storage of the state.
Quantum Simulation: A Significant Achievement
The team simulated a model called the Heisenberg chain, which is used to understand magnetism. They were particularly interested in the long-time behaviour of how spin excitations are transported across the system. In this long-time limit, quantum many-body systems enter a hydrodynamic regime and transport is described by equations that describe classical fluids.
The team was interested in a regime where super-diffusion occurs due to the underlying physics being governed by the Kardar-Parisi-Zhang equation. This equation typically describes the stochastic growth of a surface or interface, such as how the height of snow grows during a snowstorm. The propagation is known to give super diffusive transport, which becomes faster as you increase the system size. The team was able to use the quantum computer to verify this, marking the main achievement of the work.
“Generally speaking the problem of simulating the dynamics of a complex quantum system with many interacting constituents is a formidable challenge for conventional computers. Consider the 27 qubits on this particular device. In quantum mechanics the state of such a system is described mathematically by an object called a wave function. In order to use a standard computer to describe this object you require a huge number of coefficients to be stored in memory and the demands scale exponentially with the number of qubits; roughly 134 million coefficients, in the case of this simulation.”
Professor John Goold, Trinity Quantum Alliance
Challenges in Programming Quantum Computers
Programming quantum computers presents unique challenges, particularly in performing useful calculations in the presence of noise. The operations performed at the chip-level are imperfect, and the computer is very sensitive to disturbances from its laboratory environment. As a result, programmers aim to minimise the runtime of a useful programme, as this will shorten the time in which these errors and disturbances can occur and affect the result.
“IBM has a long history of advancing quantum computing technology, not only by bringing decades of research but also by providing the largest and most extensive commercial quantum programme and ecosystem. Our collaboration with Trinity College Dublin, through the MSc for Quantum Science and Technology and PhD programme, exemplifies this and I am delighted that it is already delivering promising results.”
Juan Bernabé-Moreno, Director of IBM Research UK & Ireland
The Future of Quantum Simulation
As the world moves into a new era of quantum simulation, Trinity’s quantum physicists are at the forefront, programming the devices of the future. Quantum simulation is a central pillar of research in the newly launched Trinity Quantum Alliance, which has five founding industrial partners, including IBM, Microsoft, Algorithmiq, Horizon and Moodys Analytics. The collaboration between Trinity College Dublin and IBM is already delivering promising results, exemplifying the advancements in quantum computing technology.
“Some of the simplest non-trivial quantum systems are spin chains. These are systems of little connected magnets called spins, which mimic more complex materials and are used to understand magnetism. We were interested in a model called the Heisenberg chain and we were particularly interested in the long-time behaviour of how spin excitations are transported across the system. In this long-time limit, quantum many-body systems enter a hydrodynamic regime and transport is described by equations that describe classical fluids.”
Professor John Goold, Trinity Quantum Alliance
“The biggest problem with programming quantum computers, is performing useful calculations in the presence of noise,” – Nathan Keenan, IBM-Trinity predoctoral scholar
Quick Summary
Trinity’s quantum physicists and IBM Dublin have successfully simulated super diffusion in a system of interacting quantum particles on a quantum computer, a first step in performing complex quantum transport calculations. This work, which utilised a 27-qubit quantum computer, could illuminate new aspects of condensed matter physics and materials science as quantum hardware continues to advance.
- Trinity College Dublin’s quantum physicists and IBM Dublin have successfully simulated super diffusion on a quantum computer. This is a significant step towards performing complex quantum transport calculations on quantum hardware.
- The research is part of the TCD-IBM predoctoral scholarship program, where IBM hires PhD students as employees while being co-supervised at Trinity. The findings were published in the Nature journal NPJ Quantum Information.
- The quantum computer used in the study, located in IBM’s lab in Yorktown Heights, New York, consists of 27 superconducting qubits, the building blocks of quantum logic.
- The team simulated a model called the Heisenberg chain, which is used to understand magnetism. They were particularly interested in how spin excitations are transported across the system in the long-time limit.
- The main challenge in programming quantum computers is performing useful calculations in the presence of noise, according to Nathan Keenan, an IBM-Trinity predoctoral scholar who programmed the device.
- The research is part of the newly launched Trinity Quantum Alliance, founded and directed by Prof. John Goold, which includes IBM, Microsoft, Algorithmiq, Horizon and Moodys Analytics as founding industrial partners.
