APS Journals

A significant focus in the effort to build a quantum computer, in any of the viable hardware platforms, is to understand and mitigate the primary sources of decoherence and other processes that generate qubit errors. We have collected the following papers to illustrate the key sources of infidelity researchers are attempting to understand, quantify, and moderate or eliminate, over a range of different physical platforms. These could lead to breakthrough improvements that might move one or more platforms out of the “noisy intermediate-scale quantum era".

– Andrew N. Cleland (University of Chicago, USA)

Overcoming material and architectural bottlenecks (such as losses, crosstalk, imperfections, etc.) is essential for scaling quantum hardware. This Collection highlights diverse advancements, ranging from phase-modulated control in atom arrays and optical cooling for mechanical systems to research by Nobel Laureate Michel Devoret’s team on superconducting circuits. Key breakthroughs include low-loss granular-aluminum lumped-element inductors, niobium coaxial cavities with Q-factors exceeding one billion, and optimized pump coupling for Josephson amplifiers. We also explore hybrid systems coupling superconducting chips to Rydberg atoms, reservoir engineering for battery charging, and theoretical models analyzing how oxide imperfections impact qubit performance. By resolving these bottlenecks, these works pave the way for building practical, real-world quantum devices.

– Jelena Vučković (Stanford University California, USA)

Quantum optics and photonics remain at the forefront of a myriad of next-generation technologies, offering unprecedented capabilities for secure communication, ultra-precise sensing, and quantum information processing. The ability to generate, manipulate, and detect individual photons and their quantum states has opened pathways toward practical quantum networks, enhanced imaging systems that surpass classical limits, and new kinds of integrated photonic platforms. The work highlighted in this Collection represents advances across this spectrum, from new kinds of enabling technologies and control protocols, to fundamental studies of light-matter interactions.

– Aashish Clerk (University of Chicago, USA)

Quantum algorithms are becoming increasingly hybrid, with classical components playing a crucial role. Such hybridization can happen in various ways, as illustrated in this Collection. These contributions also highlight the importance of rigorous benchmarking through the development of hard problems native to hardware graphs, which is important to having an accurate understanding of device performance. In addition, we see impressive advances at the interface between machine learning (as a building block toward AI) and quantum. Collectively, even though the quantum devices are still in their infancy, these works provide a valuable step toward developing solutions for complex and practically relevant tasks.

– Nicholas Chancellor (Durham University, UK)

This year, Physical Review Applied reported significant advances in quantum sensing, as highlighted in this Collection. Diamond nitrogen-vacancy magnetometry successfully imaged the Meissner effect and flux trapping in high-pressure superconductors. Theoretical work proposed using Stark probes to estimate nonlinear gradients within many-body systems. Meanwhile, atom interferometers achieved robustness against environmental noise through rapid sensitivity switching and nonlinear Kalman filtering. Additionally, single silicon-vacancy centers in silicon carbide were proposed for simultaneously mapping electric fields and carrier concentrations in electronic devices. These breakthroughs help bridge the gap between theoretical limits and practical application, offering improved precision for characterizing complex materials and electronic devices.

– Barry Sanders (University of Calgary, Canada)