Dark matter is a component of the universe whose presence is discernible primarily by its gravitational attraction. 30.1% of the universe is composed of dark matter.
Researchers have created a heat pump that uses light particles on a quantum scale. Scientists can now measure radio frequency signals closer to the quantum limit. Experts say this technique is useful in the search for dark matter, a component of the universe whose presence is discernible primarily by its gravitational attraction. 30.1% of the universe is composed of dark matter.
A quantum scale heat pump made from light particles has been built by physicists at TU Delft, ETH Zürich, and the University of Tübingen.
When you mix two objects of different temperatures, such as a warm glass of wine and a chilled pack, heat usually flows from the hot object (the wine) to the cold object (the chill pack). The two will eventually reach the same temperature, a process called equilibrium in physics: a balance between heat flow in one direction and heat flow in the other.
It is possible to break the balance and cause the heat to flow the “wrong” way by doing some work. Your refrigerator, for example, uses this principle to keep your food cold, and heat pumps can use it to heat your house by stealing heat from the cold air outside.
Using photons as elementary quantum particles of light, Gary Steele and his co-authors demonstrate a quantum equivalent of a heat pump by moving them from a hot to a cold object “against the flow.”
Previously, the researchers used their device as a cold bath for hot radio-frequency photons, but now they’re using it as an amplifier at the same time.
This device can detect radio frequencies better because of the amplifier built in, just as superconducting quantum processors can detect microwave signals better when amplified.
We can measure radio frequency signals closer to the quantum limit, which is very exciting because radio frequency signals are hard to measure elsewhere.
“This new measuring tool might have lots of applications, one of them being to look for dark matter,” Steele says.
According to their paper, the device is called a photon pressure circuit and is comprised of superconducting inductors and capacitors on a silicon chip with a temperature of a few millidegrees above absolute zero.
Although this sounds extremely cold, for some photons in the circuit, this temperature is extremely hot, and they are excited by the thermal energy.
In previous experiments, the researchers have used photon pressure to couple excited photons to cold photons of higher frequency, allowing them to cool hot photons into their quantum ground state.
This new work introduces a new twist: by adding an extra signal to the cold circuit, the authors are able to create an amplifying motor that heats the cold photons.
As a result, the extra signal “pump” the photons between the two circuits preferentially in one direction. It is possible to cool photons in one part of the circuit to a temperature that is colder than the other part of the circuit by pushing photons more forcefully in one direction than the other. This creates a quantum version of a superconducting heat pump for photons.
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