'Quantum Computing KPIs?' Nature magazine on performance metrics

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Quantum KPIs

Nature magazine interviewed quantum researchers about ways of comparing the performance of quantum computing systems — including the Quantum Advantage Tracker recently introduced by IBM and QCMet from a consortium in the United Kingdom. Though the value of any single metric is often debated, these tools attempt to standardize what metrics are considered, allow comparisons across different approaches to quantum computing, and reduce hype and cherry-picking of favorable results.

Read the full story in Nature.

Purified photons

Physicists at the University of Iowa demonstrated a new method of ensuring that lasers and other devices emit only a single line of photons in their operation. These purified photon sources could be a boon for quantum computing and secure optical communications. Because the color on the wavelength spectrum and the wave form generated when an atom emits more than one photon are nearly identical to the wavelength spectrum and the wave form produced by the laser beam itself, the two can be used to tune one another out and reduce unwanted scattering and extra photons, according to the team. 

This work was published in Optica Quantum.

Phase modulators

Engineers at the University of Colorado built an optical phase modulator with the lowest half-wave voltage ever developed. Fabricated in a volume CMOS foundry, the phase modulator requires 100 times less microwave power when compared to current state-of-the-art modulators with high visible-wavelength power handling. Trapped ion and neutral atom quantum computers, among many other systems, require the very precise tuning of laser frequencies provided by these types of modulators, which are typically larger and require more power.

This work was published in Nature Communications.

Microring resonator

A team at the University of Illinois Urbana-Champaign developed an on-chip microring resonator that can triple the amount of time that light survives in the resonator. These resonators could make quantum memory systems more robust and easier to manufacture and deploy.

“One of the most efficient ways to store light is by slowing it down,” Illinois’ Elizabeth Goldschmidt said. “Slowing the propagation acts like storage: if you make a long path and slow it down, it lives there for a while.”

This work was published in Nature Communications.

Quickbits

• Extreme Violations of Leggett-Garg Inequalities for a System Evolving under Superposition of Unitaries (PRL)

• Quantum-enhanced semiconductor metrology facility to launch at UT Austin with $4.8 million grant

• Penn State introduces Center for Theory of Emergent Quantum Matter

Quantum Campus is edited by Bill Bell, a science writer and marketing consultant who has covered physics and high-performance computing for more than 25 years. Disclosure statement.