Reference frames which separately store non-commuting conserved quantities

Thermodynamics of quantum systems with multiple conserved quantities

We consider a generalisation of thermodynamics that deals with multiple conserved quantities at the level of individual quantum systems. Each conserved quantity, which, importantly, need not commute with the rest, can be extracted and stored in its own battery. Unlike in standard thermodynamics, where the second law places a constraint on how much of the conserved quantity (energy) that can be extracted, here, on the contrary, there is no limit on how much of any individual conserved quantity that can be extracted. However, other conserved quantities must be supplied, and the second law constr…

Non-commuting two-local Hamiltonians for quantum error suppression

Physical constraints make it challenging to implement and control many-body interactions. For this reason, designing quantum information processes with Hamiltonians consisting of only one- and two-local terms is a worthwhile challenge. Enabling error suppression with two-local Hamiltonians is particularly challenging. A no-go theorem of Marvian and Lidar [Physical Review Letters 113(26), 260504 (2014)] demonstrates that, even allowing particles with high Hilbert-space dimension, it is impossible to protect quantum information from single-site errors by encoding in the ground subspace of any Ha…

Quantum Reference Frames and Their Applications to Thermodynamics

We construct a quantum reference frame, which can be used to approximately implement arbitrary unitary transformations on a system in the presence of any number of extensive conserved quantities, by absorbing any back action provided by the conservation laws. Thus, the reference frame at the same time acts as a battery for the conserved quantities. Our construction features a physically intuitive, clear and implementation-friendly realisation. Indeed, the reference system is composed of the same types of subsystems as the original system and is finite for any desired accuracy. In addition, the…

具有非厄米四次项的一维玻色紧束缚链中的守恒量

Conserved quantities in a bosonic tight-binding chain with non-Hermitian quartic terms

本文研究非厄米玻色子晶格中的局域守恒量，通过傅里叶变换和三角恒等式推导出相互对易的守恒量族，并扩展到多种相互作用形式，提供统一构造框架。

非对易测量的量子能量学

Quantum energetics of a non-commuting measurement

本研究通过电路量子电动力学实验，探究非对易测量中能量转移机制，发现探针频移与量子比特能量变化平衡，为量子测量基础提供新见解。

弱不可积边界杂质模型中缓慢衰减的零模

Slowly decaying zero mode in a weakly non-integrable boundary impurity model

本文研究半无限横场伊辛模型在边界可积性破缺微扰下边缘零模的衰减机制，发现其通过弛豫到非局域准守恒算符而衰减，并在热力学极限下用Krylov空间玩具模型恢复费米黄金定则。