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Quantum Thermometer Designed to Quantify the Temperatures of Space and Time

A quantum thermometer has been designed by an international group of researchers, including specialists from the University of Adelaide, to quantify the ultra-cold temperatures of time and space foretold by Einstein and the laws of quantum mechanics.

Image Credit: University of Adelaide.

Dr James Q. Quach, Ramsay Fellow at the School of Physical Sciences and the Institute for Photonics and Advanced Sensing (IPAS) at the University of Adelaide, headed the study.

We have designed a quantum thermometer that can measure extremely small changes in temperature. The theoretical design of the quantum thermometer is based on the same technology used to build quantum computers.

Dr. James Q. Quach, Study Lead and Ramsay Fellow, School of Physical Sciences, University of Adelaide

Einstein projected that the rate at which one perceives time to pass is reliant on the speed at which one is traveling: a person moving extremely fast ages at a slower rate than someone not moving. This resulted in his Theory of General Relativity, which states that time and space together serve like a cloth that can flex and warp.

The association between temperature and acceleration is akin to the association between time and speed. Different observers traveling at different speeds would perceive different, albeit minute, differences in temperatures.

In 1976 Canadian physicist William Unruh combined Einstein’s work with the other fundamental theory of modern-day physics, quantum mechanics, and predicted that fabric of space-time has a very low temperature. Intriguingly this temperature changed depending on how fast you are moving. To see this change in temperature, you would have to move extremely fast.

Dr. James Q. Quach, Study Lead and Ramsay Fellow, School of Physical Sciences, IPAS, University of Adelaide

“To see even one degree change in temperature you would have to move close to the speed of light. Up until now, these extreme speeds have prevented researchers from verifying Unruh’s theory,” Dr. Quach added.

Dr. Quach and his contemporaries Professor William Munro from NTT Basic Research Laboratories in Japan and Professor Timothy Ralph from the University of Queensland discussed their work in an article published in the journal Physical Review Letters.

In theory a quantum thermometer does not need to physically accelerate, instead it uses a magnetic field to accelerate the internal energy gap of the device. The quantum thermometer can be built with current technology.

Dr. James Q. Quach, Study Lead and Ramsay Fellow, School of Physical Sciences, IPAS, University of Adelaide

The group’s study would have crucial repercussions for future research. The quantum thermometer could perhaps be used to quantity ultracold temperatures and with a precision that traditional thermometers cannot.

Journal Reference:

Quach, J. Q., et al. (2022) Berry Phase from the Entanglement of Future and Past Light Cones: Detecting the Timelike Unruh Effect. Physical Review Letters.


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