Quantum as analog? New techniques from MIT

Quantum Campus shares the latest in quantum science and technology from university campuses. We publish on Fridays and are always looking for news from researchers across the country. Want to see your work featured? Submit your ideas to the editor.

Quantum as analog

An MIT team published a new technique for simulating how electrons move in synthetic electromagnetic fields on quantum processors. The simulated field is broadly adjustable, allowing scientists to explore a range of material properties. The paper appeared in Nature Physics, and it demonstrated the technique on 16 qubits.

The team used the small-scale quantum processor as an analog device to emulate the material system. They altered how adjacent qubits were coupled to recreate the complex hopping behavior that electromagnetic fields cause in electrons.

“General-purpose digital quantum simulators hold tremendous promise, but they are still a long way off. Analog emulation is another approach that may yield useful results in the near-term, particularly for studying materials. It is a straightforward and powerful application of quantum hardware,” said Ilan Rosen, a postdoc and lead author on the paper.

Read the full announcement from MIT. 

Enigmatic thin films

New findings on the magnetic properties of iron-tin thin films and kagome magnets could allow for new tailored materials for quantum devices and superconductors, according to a team from Rice.

Led by Ming Yi and Zheng Ren, researchers found that these “enigmatic” materials’ magnetic properties arise from localized electrons, not mobile electrons as scientists previously thought. Analyzing the thin film’s electronic structure, they found that — even at elevated temperatures — kagome flat bands remained split. That indicates that localized electrons drive magnetism in the material. The study also revealed that some electron orbitals showed stronger interactions than others, providing perspective on how electron interactions influence the behavior of kagome magnets.

Read the story from Rice and the paper in Nature Communications.

Adaptive variational algorithms

A group from Virginia Tech, North Carolina State, and University of California Santa Barbara received $5 million from the Department of Energy to develop adaptive variational algorithms capable of quickly learning from and acting on data acquired from both the application and the hardware during runtime. This setup will allow the algorithms to rapidly converge to the solution.

The team will use DOE quantum hardware and cloud-based quantum simulators in their work, and they will focus on applications in chemistry, machine learning, and materials physics.

Read Virginia Tech’s announcement of the grant.

Parallel quantum-enhanced sensing

Using bright twin beams of light to probe a four-sensor quadrant plasmonic array, researchers from Oak Ridge National Lab and the University of Oklahoma showed it is possible to independently and simultaneously measure local changes in the refractive index for all four sensors with a quantum advantage. Their results were published in ACS Photonics. 

The research led to quantum enhancement in sensitivity for all four sensors in the range of 22 to 24 percent over the corresponding classical configuration.

“Typically, you use the fact that you have correlations in time and take advantage of noise levels below the classical limit, that is squeezing, to enhance a measurement and obtain a quantum enhancement,” said Oak Ridge researcher Alberto Marino. “What we did in this case was combine both the temporal and spatial correlations to probe several sensors at the same time and get a simultaneous quantum enhancement for all of them.”

Read the Oak Ridge announcement.

Quickbits

• NIST releases a second set of algorithms for its post-quantum cryptographic standardization process

• International team publishes quantum optimization review paper

• UK opens new National Quantum Computing Centre

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