Unlocking the Potential of Quantum Devices: Describing Spin-Boson Systems
Many of today’s quantum devices rely on collections of qubits, also known as spins. These quantum bits possess only two energy levels, represented as ‘0’ and ‘1’. However, spins in real devices interact with light and vibrations known as bosons, creating complexity in calculations. In a groundbreaking publication in Physical Review Letters, researchers in Amsterdam showcase a method to describe spin-boson systems, paving the way for efficient configuration of quantum devices in desired states.
Quantum devices harness the peculiar behavior of quantum particles to accomplish tasks that surpass the capabilities of traditional machines. This includes quantum computing, simulation, sensing, communication, and metrology. These devices come in various forms, from superconducting circuits to lattices of atoms or ions controlled by lasers or electric fields.
Despite their diverse physical structures, quantum devices are often simplified as interacting two-level quantum bits or spins. However, these spins interact with elements in their environment, such as light in superconducting circuits or oscillations in atom or ion lattices. Photons and phonons are examples of bosons.
Unlike spins with only two energy levels, bosons have infinite energy levels. This poses challenges in describing spins coupled to bosons. In their latest study, physicists Liam Bond, Arghavan Safavi-Naini, and Jiří Minář from the University of Amsterdam adopt non-Gaussian states to describe spin-boson systems. These states are superpositions of simpler Gaussian states.
In their research, the scientists illustrate different quantum states of the spin-boson system. “A Gaussian state appears as a plain red circle, lacking the intricate blue-red patterns,” explains Liam Bond, a PhD candidate. By overlapping Gaussian states into superpositions, complex patterns emerge, enabling the description of a wider range of quantum states.
Bond elaborates on their method, stating, “Classical computers often struggle to process these intricate patterns. Our approach identifies the essential patterns, allowing the study and design of unique quantum states.” This method surpasses traditional protocols, offering efficient quantum state preparation beneficial for quantum simulation and error correction.
The researchers also demonstrate the use of non-Gaussian states to prepare ‘critical’ quantum states, enhancing quantum sensor sensitivity. While these findings mark a significant advancement, the researchers acknowledge the need to extend their method to multiple spins and bosonic modes concurrently, as well as address environmental disturbances in spin-boson systems.