Many quantum devices today rely on collections of qubits or spins with only two energy levels, ‘0’ and ‘1’. However, these spins also interact with light and vibrations known as bosons, making calculations complex. In a new study published in Physical Review Letters, researchers in Amsterdam have developed a way to describe spin-boson systems, enabling the efficient configuration of quantum devices in desired states. Quantum devices utilize the unique behavior of quantum particles for tasks such as quantum computing, sensing, and communication. These devices can take various forms, such as superconducting circuits or lattices of atoms held by lasers or electric fields.
Quantum devices are typically simplified as interacting two-level spins, which also interact with light and vibrations in their surroundings, such as photons and phonons, both examples of bosons. While spins have only two energy levels, bosons have infinite possibilities, making computational tools for describing spins coupled to bosons limited. Physicists at the University of Amsterdam use non-Gaussian states to describe systems composed of spins and bosons. These non-Gaussian states are superpositions of simpler Gaussian states, allowing for a diverse set of quantum states to be described.
Researchers have found that non-Gaussian states reveal intricate patterns in the quantum state of the spin-boson system, unlike Gaussian states that appear plain. By identifying crucial patterns and ignoring irrelevant ones, the researchers can efficiently study these quantum systems and design new ways of preparing interesting quantum states. This new approach can outperform traditional protocols in preparing quantum states, which could be beneficial for applications like quantum simulation and error correction.
The method demonstrated in the study has shown promising results for a single spin, but there are challenges in extending it to multiple spins and bosonic modes simultaneously. Additionally, accounting for the effects of the environment on the spin-boson systems is another active area of research. The ability to prepare ‘critical’ quantum states using non-Gaussian states is essential as these states can enhance the sensitivity of quantum sensors. Future research aims to build on these findings to achieve more ambitious goals in quantum state preparation and handling multiple spins and bosonic modes simultaneously.