A team of researchers has precisely measured the force on a scale a trillion times smaller than is possible with standard instruments. This means that microwave radiation can be evaluated more accurately in quantum physics experiments.
Being able to measure energy at extremely low levels is useful to scientists building quantum systems — systems that are incredibly small and usually incredibly cold in terms of their temperature. Now we can take these measurements with much more precision.
For example, the new system could be used to better prepare and calibrate qubits — the particles at the center of quantum computers that replace classical qubits — to ensure that they work as intended and that the readings they produce are correct.
“Commercial power sensors typically measure power in one milliwatt scale,” He says Russell Lake, a senior scientist at quantum technology company Bluefors in Finland.
“This pressure gauge does this accurately and reliably at 1 femtowatt or less. That’s a trillion times less energy than is used in typical energy calibrations.”
In quantum experiments, energy is measured using a special thermometer called a Pressure-gauge. It tracks temperature through a tiny strip of material — usually a metal or semiconductor — that changes its electrical resistance as it absorbs energy.
The researchers added a heater of known current and voltage to the new system. By knowing precisely how much heat was introduced, scientists detected very small energy shifts by very weak microwaves.
Part of the reason quantum physics is so difficult is that quantum systems are very fragile, and can be broken or interfered with by the smallest perturbations, including the instruments we use to try to measure them. One way the new approach can help is by detecting these disorders.
“For accurate results, the measuring lines used to control the bits must be at very low temperatures, free of any thermal photons and excess radiation,” He says Quantum physicist Mikko Möttönen of Aalto University in Finland.
“Now, with this pressure gauge, we can actually measure the radiation temperature without interference from the qubit circuit.”
The new setup is known as a nanoscale, and early tests on weak microwaves passing through a radio frequency transmission line showed that the device could precisely record changes in energy.
This work builds on previous search in creating a strain meter capable of measuring the qubit’s energy state. This approach is scalable and does not use much power while eliminating any potential qubit interference.
Urinemeters can be used in a variety of scenarios, including as part of deep space telescopes, but if they can be used practically on qubits, it means we’re one step closer to fully realized quantum computing systems.
“Microwave measurement occurs in radio communications, radar technology, and many other fields,” Add lake. “They have their ways of making accurate measurements, but there was no way to do the same when measuring the very weak microwave signals of quantum technology.”
“The barometer is an advanced diagnostic tool that has been missing from the quantum technology toolbox until now.”
Research published in Review of scientific tools.
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