Routing signals and isolating them against noise and back-relections is essential in many practical situations in classical communication as well as in quantum processing. In a theory-experiment collaboration, a team led by Andreas Nunnenkamp from the University of Vienna and Ewold Verhagen based at AMOLF, Amsterdam, achieved the unidirectional transport of signals in pairs of “one-way roads.” This research was published in Nature Physics opens up new possibilities for more flexible signaling devices.
Devices that allow the routing of signals, for example carried by light or sound waves, are needed in many practical situations. This is, for example, the case of quantum information processing, where the states of the quantum computer must be amplified in order to read them—without noise from the amplification process damaging them. That’s why devices that allow signals to travel in a single path such as isolators or circulators are increasingly sought after.
However, currently such devices are lost, bulky, and require large magnetic fields that break the time-varying symmetry to achieve unidirectional behavior. These limitations have prompted intense efforts to find alternatives that take up less space and do not rely on magnetic fields.
A new study published in Nature Physics introduces a new class of systems characterized by a phenomenon the authors call “quadrature nonreciprocity.” Quadrature nonreciprocity exploits the interference between two different physical processes. This allows the unidirectional transmission of signals without time-reversal breaking and leads to a different dependence on the phase, ie, the quadrature, of the signal.
“In these devices, the transmission depends not only on the direction of the signal, but also on the signal quadrature” said Dr. Clara Wanjura, the theoretical lead author of the study. “This realizes a ‘dual carriageway’ for signals: one quadrature is transmitted in one direction and the other quadrature in the opposite direction. The time-reversal symmetry then enforces that the quadratures always travel in pairs in opposite directions in two separate lanes.”
The experimental group of AMOLF demonstrated this phenomenon experimentally in a nanomechanical system where the interactions of the mechanical vibrations of small silicon strings are orchestrated by laser light. The laser light forces the strings, thereby mediating the interactions between their different ‘tones’ of vibration.
Dr. Jesse Slim, the experimental lead author of the study says, “We have developed a versatile experimental toolbox that allows us to control the two different types of interactions required to implement quadrature nonreciprocity. This way it can we will reveal the resulting unidirectional transport of signals experimentally.”
The work opens up new possibilities for signal routing and quantum-limited amplification, with potential applications in quantum information processing and sensing.
Clara C. Wanjura et al, Quadrature nonreciprocity in bosonic networks without violating time-reversal symmetry, Nature Physics (2023). DOI: 10.1038/s41567-023-02128-x
Citation: Engineering dual carriageways for signals: Research expands possibilities for more flexible signaling devices (2023, July 13) retrieved 13 July 2023 from https://phys.org/news/2023-07-dual- carriageways-possibilities-flexible-devices. html
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