The next generation of computing and information processing lies in the
intriguing world of quantum mechanics. Quantum computers are expected to be
capable of solving large, extremely complex problems that are beyond the
capacity of today's most powerful supercomputers.
New research tools are needed to advance the field and fully develop quantum
computers. Now Northwestern University researchers have developed and tested
a theoretical tool for analyzing large superconducting circuits. These
circuits use superconducting quantum bits, or qubits, the smallest units of
a quantum computer, to store information.
Circuit size is important since protection from detrimental noise tends to
come at the cost of increased circuit complexity. Currently there are few
tools that tackle the modeling of large circuits, making the Northwestern
method an important contribution to the research community.
"Our framework is inspired by methods originally developed for the study of
electrons in crystals and allows us to obtain quantitative predictions for
circuits that were previously hard or impossible to access," said Daniel
Weiss, corresponding and first author of the paper. He is a fourth-year
graduate student in the research group of Jens Koch, an expert in
superconducting qubits.
Koch, an associate professor of physics and astronomy in Weinberg College of
Arts and Sciences, is a member of the Superconducting Quantum Materials and
Systems Center (SQMS) and the Co-design Center for Quantum Advantage (C2QA).
Both national centers were established last year by the U.S. Department of
Energy (DOE). SQMS is focused on building and deploying a
beyond-state-of-the-art quantum computer based on superconducting
technologies. C2QA is building the fundamental tools necessary to create
scalable, distributed and fault-tolerant quantum computer systems.
"We are excited to contribute to the missions pursued by these two DOE
centers and to add to Northwestern's visibility in the field of quantum
information science," Koch said.
In their study, the Northwestern researchers illustrate the use of their
theoretical tool by extracting from a protected circuit quantitative
information that was unobtainable using standard techniques.
Details were published today (Sept. 13) in the open access journal Physical
Review Research.
The researchers specifically studied protected qubits. These qubits are
protected from detrimental noise by design and could yield coherence times
(how long quantum information is retained) that are much longer than current
state-of-the-art qubits.
These superconducting circuits are necessarily large, and the Northwestern
tool is a means for quantifying the behavior of these circuits. There are
some existing tools that can analyze large superconducting circuits, but
each works well only when certain conditions are met. The Northwestern
method is complementary and works well when these other tools may give
suboptimal results.
The title of the paper is "Variational tight-binding method for simulating
large superconducting circuits."
Reference:
D. K. Weiss et al, Variational tight-binding method for simulating large
superconducting circuits, Physical Review Research (2021).
DOI: 10.1103/PhysRevResearch.3.033244
Tags:
Physics