iQ@WSU

The classical nature of our intuition. Newton formulated a description of dynamics based relating force to mass and acceleration. The resulting theory, called classical mechanics, does an amazing job of characterizing our world on scales that we are familiar with: the motions of cars, the stability of buildings, even the movements of planets and motion of water and air. This is the science of our every-day experience, and the science for which we have the best intuition.

Rapid motion over large scales. The theory of classical mechanics is not complete, however, and breaks down in two extreme limits: when we move very fast – close to the speed of light – the absolute notions of space and time become relative, and Einstein’s theory of relativity leads to counter intuitive effects like time dilation: e.g. clocks on satellites orbiting the earth run slower than those on earth.

Slow motion at very small scales. At the other extreme, when things move very slowly, or when we look at very small scales (atomic and subatomic), Newton’s laws also need correcting, and the best description we have currently lies in the theory of quantum mechanics, where particles are described by wavefunctions, and measurements become intrinsically random in character. Since these scales like far from our every-day experience, quantum mechanics, like relativity, has many features that are highly counterintuitive: wave-particle duality, entanglement, correlations between experiments that are far apart, etc.

Why is developing new quantum technology hard? As demonstrated by the success of classical mechanics, there is a natural tendency for the properties that emerge from quantum mechanics to behave classically. Thus, to tease out new quantum effects, we must find ways of tuning or designing our systems to eschew these natural classical tendencies. The results can be impressive, e.g. extremely precise clocks and highly sensitive detectors, but at the cost of requiring highly controlled fabrication, or extremely low temperatures (cryogenics) to keep the devices operating in the quantum regime.

Ultra-Cold Atoms

In the Fundamental Quantum Physics Lab, run by Physics Professor Peter Engels – the Boeing Professor Boeing Endowed Professor in Advanced Material Science – atoms are cooled to nano-Kelvin temperatures where their quantum wave-nature manifests. Cold atoms provide a versatile platform for studying fundamental physics. This is the platform that led to the development of accurate and portable atomic clocks, which are a key component of GPS systems, allowing them to compensate for effects from general and special relativity that cause time to progress at a different rate on satellites. As an impressive example of the maturity and robustness of this technology, an ultracold-atom platform has been transported to the International Space Station where it can be remotely operated to study quantum dynamics in microgravity. Prof. Engels is a part of this Cold Atom Lab (CAL) collaboration led by NASA.

Professor Michael McNeil Forbes (theory) in Physics uses cold atoms as an analog quantum computer to simulate nuclear physics and nuclear astrophysics, especially properties of superfluid dynamics in neutron stars. The Forbes-Engels collaboration has also studied negative-mass hydrodynamics (featured on the BBC), gravitational caustics, atom-interferometric imaging, and compressible quantum turbulence. Prof. Forbes also collaborates with groups at UW through his affiliate appointment: specifically with Prof. Sanjay Reddy, director of the national Institute for Nuclear Theory on aspects of nuclear astrophysics; Prof. Subhadeep Gupta, chair of the Physics department, who runs cold-atom experiments that study fermionic superfluids; and with long-time collaborator Prof. Aurel Bulgac in the Nuclear Theory Group studying nuclear structure (e.g. they co-developed the SeaLL nuclear energy density functionals, and asymmetric superfluid local density approximation (ASLDA) for modelling the dynamics of superfluids).

Professor Qingze Guan (theory) in Physics – early-career – uses cold atoms as a tool to study fundamental quantum effects for sensing applications.

Professor Yefeng Mei (experiment) in Physics – early-career – is building another ultra-cold atom experiment to study Rydberg atoms, which are unique in having very weakly bound electrons that are extremely sensitive to electromagnetic (EM) fields.

Professor Steven Tomsovic (theory) in Physics uses semi-classical techniques, random matrix theory, and ab-initio techniques to study quantum chaos and how to control quantum systems.

Non-linear Optics: Quantum Transduction

Regents Professor Mark Kuzyk in Physics works with non-linear optical systems, seeking to maximize and manipulate the nonlinear response (see the Kuzyk quantum gap) of materials to generate entanglement between colours. Their approach is to tie quantum systems together by taking advantage of Prof. Kuzyk’s expertise in fabricating, assembling, and characterizing the quantum-based nonlinear optical components that will form the basis for quantum transduction. Theory support will be provided by the groups of Prof. Forbes, who studies many-body dynamics in cold-atoms and nuclear physics, Prof. Tomsovic, who uses semiclassical techniques to quantify many-body quantum effects, and Prof. Guan, who studies quantum dynamics for quantum sensing, quantum metrology, nonlinear phenomena in cold-atoms, and few-body physics. These three theory groups have close connections with experiments around the world. To connect this system with low-temperature platforms, the team is augmented by Prof. Gupta, who implements high-speed cryo-electronic interfaces between quantum and classical systems.

While linear optics plays a fundamental role in quantum technology, nonlinear-optical effects have largely been neglected as a tool for quantum computing. Nonlinear elements allow one to produce and entangle different frequencies, enabling color to be used as a new quantum degree of freedom (qudits) in addition to polarization currently used for photonic qubits. Colored qudits allow for more compact and efficient implementations of synthetic dimensions for quantum simulation, improved sensing for metrology, and may enable more practical quantum operations and error correction.

As optical technologies already form the basis for quantum communication networks, a nonlinear optical platform for quantum computing is easy to integrate with quantum networks and to connect with other quantum devices, enabling “quantum transduction” – the transference of quantum information from one platform to another. Another fundamental advantage of nonlinear optics is its ability to operate at room temperature, drastically reducing the cost to both explore and deploy these systems.

An example of a unique technology created at WSU exploits the interplay between mechanical and nonlinear optical properties of materials, providing a natural mechanism to harness one of the most challenging aspects of quantum computing – classical control of quantum systems. Nonlinear optics may provide a new way to input classical data into quantum systems.

Quantum Sensors and Cryoelectronics

Professor Sukanta Bose (theory) in Physics is a member of the LIGO collaboration which uses quantum-enhanced sensing to listen to ripples in spacetime from merging black-holes and neutron stars. He collaborates with Prof. Forbes to use signals from LIGO to place constraints on neutron-rich matter.

Magnetic resonance studies of spin systems in the group of Professor Brian Saam offer another highly sensitive platform with applications to medical imaging of the lungs, and guidance systems.

The Rydberg atoms studied by Prof. Mei are unique in having very weakly bound electrons that are extremely sensitive to electromagnetic (EM) fields. These form a basis for highly-sensitive EM sensors. Prof. Mei and Professor Subhanshu Gupta (experiment) in EECS collaborate to connect these sensors to conventional electronics systems using Prof. Gupta’s expertise in cryo-electronics to understand how the behaviour of electronic components change at the cyrogentic temperatures needed to interface with quantum sensors and quantum computing devices.

Professor Praveen Sekhar (experiment) at the Vancouver Campus, has research interests in quantum sensing, and the internet of things, involving integration of sensors and antennas. Quantum sensors require calibration far less frequently and are one to two orders of magnitude more sensitive than conventional technology, enabling measurements that are more granular and accurate. The goal of his project is to advance food safety through the development of electrochemical quantum sensors, by investigating the feasibility of electrochemical tunnelling sensor to precisely detect biogenic amines to indicate spoilage in cold storage foods.

Mathematics

Professors Bala Krishnamoorthy (Vancouver) in Mathematics and Kevin Vixie (Pullman) in Mathematics study topological data analysis, information theory, and geometric analysis, supporting many aspects of WSU’s quantum research program. They also ensure that students develop a strong and intuitive understanding of the mathematical frameworks that form the foundation for quantum science, data analysis, and statistical learning theory.

Adjuncts

Prof. Bose also collaborates with Michael Landry, Adjunct professor in the Physics department, and head of the LIGO Hanford site in the Tri-Cities region. Quantum research supports the aims of the LIGO project by providing quantum-enhanced sensing using squeezed states of light. In turn, LIGO observations help constrain properties of nuclear many-body systems, especially in the neutron rich matter found in neutron stars.

Profs. Engels and Forbes collaborate closely with Maren Mossman and Sean Mossman, former members of the Fundamental Quantum Physics Lab who now work at the University of San Diego.

WSU also collaborates with Yale Fan at the neighbouring University of Idaho. Yale uses properties of quantum error correction to study general relativity and cosmology through connections afforded by holographic dualities.

Quantum Applications

The fundamental quantum research performed within the iQ@WSU supports many applications, including nuclear energy – both fusion (studied by Professor Christopher Keane in Physics) and fission (studied by Prof. Forbes) – and solar energy production, studied by Professor Brian Collins in Physics. It also lies at the core of the material properties studied by Professors Matthew McCluskey (experiment) and Yi Gu (experiment) in Physics.