Nonunitary gate operations by dissipation engineering

Abstract

Irreversible logic is at odds with unitary quantum evolution. Emulating such operations by classical measurements can result in disturbances and high resource demands. To overcome these limitations, we propose protocols that harness dissipation to realize the nonunitary evolution required for irreversible gate operations. Using additional excited states subject to decay, we engineer effective decay processes that perform the desired gate operations on the smallest stable Hilbert space. These operate deterministically and in an autonomous fashion, without the need for measurements. We exemplify our approach considering several classical logic operations, such as the OR, NOR, and XOR gates. Towards experimental realization, we discuss a possible implementation in quantum dots. Our study shows that irreversible logic operations can be efficiently performed on realistic quantum systems and that dissipation engineering is an essential tool for obtaining nonunitary evolutions. The proposed operations expand the quantum engineers' toolbox and have promising applications in NISQ algorithms and quantum machine learning.

Open quantum behaviour manifested in the double-slit experiment

“…Since it is common to consider situations in which the timescale of decoherence is much smaller than the timescale of dissipation, the latter effect is generally neglected [13,22]. However, the consequences of energy exchange between the quantum system and its environment are of interest in quantum technology and quantum thermodynamics [23][24][25][26]. Understanding dissipation and decoherence, for instance in quantum information processing and quantum computation, is crucial for mitigating errors, designing robust systems, modeling noise effects, and implementing efficient quantum error correction techniques [27].…”