Cleaning up quantum devices

February 3, 2017
Cleaning up quantum devices
Artistic impression of noise in quantum circuits. Credit: National Physical Laboratory

A paper, based on NPL collaborative research, has been published in the journal Physical Review Letters The work paves the way for the identification and elimination of small amounts of surface defects whose presence on the surfaces of solid state quantum devices is detrimental to their performance.

The research was the result of a fruitful collaboration between NPL's Quantum Detection Group, the Quantum Device Physics Laboratory at Chalmers University of Technology and the Institute of Chemical Physics at the University of Latvia.

The advancement of computing faces a tremendous challenge in improving the reproducibility and robustness of quantum circuits. One of the biggest problems in this field is the presence of noise intrinsic to all these devices, the origin of which has puzzled scientists for many decades.

The current research shows that the same hyperfine signatures of atomic Hydrogen used by astronomers to study the violent birth of distant stars reveal themselves in very small quantities in these tiny ultracold quantum circuits.

The identification of these elusive yet detrimental spins by shed new light on the origin of magnetic noise in , showing great promise for its mitigation. Remarkably, highly reactive physisorbed atomic hydrogen, a by-product of water dissociation, is stable in very small densities on the surface of these devices, closely matching the ubiquitous density of previously unknown paramagnetic species believed to be responsible for flux noise.

The detection technique presented in the paper can also be applied in a wider context to study the surface chemistry of commonly used oxide surfaces; important for many other fields such as catalysis, sensing, medical imaging and environmental technologies.

The paper was selected as an 'Editor's Suggestion', and was published together with another study by UCSB/Google that finds similar spectroscopic fingerprints in the noise spectra of superconducting qubits. Together these findings make a significant step towards understanding and eliminating and decoherence in superconducting qubits and other quantum devices.

Explore further: Researchers make leap in measuring quantum states

More information: S.‚ÄČE. de Graaf et al. Direct Identification of Dilute Surface Spins on: Origin of Flux Noise in Quantum Circuits, Physical Review Letters (2017). DOI: 10.1103/PhysRevLett.118.057703

Related Stories

Tuning in to noisy interference

July 29, 2011

Establishing a detailed knowledge of the noise properties of superconducting systems is an important step towards the development of quantum computers, which will enable new types of computing. However, the signals of these ...

Recommended for you

Scientists update four key fundamental constants

October 23, 2017

Paving the way for transforming the world's measurement system, an international task force has determined updated values for four fundamental constants of nature. The updated values comprise the last scientific piece of ...

Scientists discover superconductor with bounce

October 23, 2017

The U.S. Department of Energy's Ames Laboratory has discovered extreme "bounce," or super-elastic shape-memory properties in a material that could be applied for use as an actuator in the harshest of conditions, such as outer ...

Experiment provides deeper look into the nature of neutrinos

October 23, 2017

The first glimpse of data from the full array of a deeply chilled particle detector operating beneath a mountain in Italy sets the most precise limits yet on where scientists might find a theorized process to help explain ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.