Physicists Build a Quantum Bit That Can Search for Dark Matter

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Qubit on Sapphire Substrate

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A qubit (the little rectangular shape) is set onto a sapphire substrate, which sits upon a fingertip to reveal scale. Fermilaband University of Chicago researchers utilized a qubit comparable to this one to establish a method that will accelerate the look for axion dark matter and concealed photons. Credit: Photo by Reidar Hahn, Fermilab

Qubits provide a quickly, extremely reputable method to resolve among the terrific secrets in physics.

Some type of undetectable product is out there impacting the movements of stars and galaxies, however so far, nobody has actually had the ability to straight discover the compound—called dark matter—itself. But some are hoping that we can tap the growing field of quantum science to lastly discover it.

Scientists at the U.S. Department of Energy’s Fermi National Accelerator Laboratory and the University of Chicago have actually shown a brand-new method based upon quantum innovation that will advance the look for dark matter, which represents 85% of all matter in deep space.

“We know that there’s a huge amount of mass all around us that isn’t made of the same stuff you and I are made of,” stated Fermilab researcher Aaron Chou, co-author of a paper released in Physical Review Letters on the brand-new method. “The nature of dark matter is a really compelling mystery that a lot of us are trying to solve.”

In specific, there are 2 type of subatomic particles that researchers have actually assumed as possible manner ins which dark matter might appear. The partnership has actually established brand-new gadgets based upon quantum computing bits that will have the ability to discover the weak signals discharged by either of these particles, if they exist: one called an “axion,” and the other called a “hidden photon,” a particle that potentially engages with the photons— particles of light—of the noticeable universe.

“The nature of dark matter is a really compelling mystery that a lot of us are trying to solve.”

Aaron Chou, Fermilab researcher

The method now shown by the Fermilab-University of Chicago group might make it possible for look for dark matter to continue 1,000 times faster than previous techniques.

Using light to discover dark particles

Physicists have actually made little development in spotting axions given that their presence was proposed more than 30 years earlier.

“Experiments using conventional techniques were just nowhere near what they needed to be for us to be able to detect higher-mass axion dark matter,” Chou stated. “The noise level is way too high.”

But over the previous years, researchers have actually ended up being progressively proficient at utilizing the homes of quantum mechanics, the laws that govern the unusual habits of particles at the tiniest levels of deep space, in order to develop brand-new innovation. One such accomplishment is a “qubit,” or quantum computing bit. These can be extremely conscious even the tiniest perturbations—which is precisely what you desire in a detector.

In the group’s brand-new method, qubits are created to discover the photons that would be produced when dark matter particles engage with an electro-magnetic field. A specifically developed gadget called a superconducting cavity offers a method to build up and keep the signal photon. The qubit, placed into the cavity, then determines the photon.

The method will benefit the look for any dark matter prospect due to the fact that when undetectable particles transform into photons, they can be found.

Superconducting Microwave Cavity Dark Matter Signal

The blue cylinder in this diagram represents a superconducting microwave cavity utilized to build up a dark matter signal. The purple is the qubit utilized to determine the state of the cavity, either 0 or 1. The worth describes the variety of photons counted. If the dark matter has actually effectively transferred a photon in the cavity, the output would determine 1. No deposition of a photon would determine 0. Credit: Image thanks to Akash Dixit

The essential to the method’s level of sensitivity is its capability to remove false-positive readings, the researchers stated. Conventional methods damage the photons they determine. But the brand-new method can penetrate the photon without damaging it. Making duplicated measurements of the exact same photon, throughout its 500-split second life time, offers insurance coverage versus incorrect readings.

“To make a measurement of the photon once with the qubit takes about 10 microseconds, so we can make about 50 repeated measurements of the same photon within its lifetime,” stated Akash Dixit, a doctoral trainee in physics at the University of Chicago and co-author.

The Fermilab-University of Chicago group’s method likewise lowers the sound that conceals the signal.

“It’s a much more clever and cheaper way to get the same large improvements in sensitivity,” Chou stated. “Now, the level of the static noise has been reduced by so much that you have a chance to actually see the very first small wiggles in your measurements due to the very, very tiny signal.”

“Where the conventional method may generate one photon of noise with every measurement, in our detector you get one photon of noise every thousand measurements you make,” Dixit stated.

Dixit and his coworkers adjusted their method from one established by atomic physicist Serge Haroche, who shared the 2012 Nobel Prize in Physics for his accomplishment.

Ferreting out axions and concealed photons

Superconducting microwave cavities are crucial to the brand-new method. The cavity utilized in the experiment is made from extremely pure—99.9999%—aluminum. At very low temperature levels, the aluminum ends up being superconducting, a home that extends the durability of quantum bits, which by their nature are short-term.

“The benefit we get is that, once you—or dark matter—puts a photon in the cavity, it’s able to hold the photon for a long time,” Dixit observed. “The longer the cavity holds the photon, the longer we have to make a measurement.”

“The longer the cavity holds the photon, the longer we have to make a measurement.”

UChicago college student Akash Dixit

The method is 36 times more conscious the particles than the quantum limitation, a criteria of traditional quantum measurements.

If axions exist, the present experiment offers a one-in-10,000 opportunity that it would discover a photon produced by a dark matter interaction.

“To further improve our ability to sense such a rare event, the temperature of the photons needs to be lowered,” stated David Schuster, associate teacher of physics at UChicago and a co-author of the brand-new paper. Lowering the photon temperature level will even more increase level of sensitivity to all dark matter prospects, consisting of concealed photons.

The photons in the experiment have actually been cooled to a temperature level of roughly 40 millikelvins (minus 459.60 degrees Fahrenheit), simply a touch above outright no. The scientists want to go as low as the operating temperature level of 8 millikelvins (minus 459.66 degrees Fahrenheit). At this point, the environment for looking for dark matter would be clean, successfully devoid of background photons.

“While there’s definitely still a ways to go, there’s reason to be optimistic,” stated Schuster, whose research study group will use the exact same innovation to quantum computing. “We’re using quantum information science to help the dark matter search, but the same kind of background photons are also a potential error source for quantum computations. So this research has uses beyond fundamental science.”

“While there’s definitely still a ways to go, there’s reason to be optimistic.”

Assoc. Prof. David Schuster

Schuster stated the task offers a great example of the kind of partnership that makes good sense to do in between a university laboratory and a nationwide laboratory.

“Our university lab had the qubit technology, but in the long term by ourselves, we were not really able to do any kind of dark matter search at the level needed,” he stated. “That’s where the national-lab partnership plays an important role.”

The reward from this cross-disciplinary effort might be substantial.

“There’s just no way to do these experiments without the new techniques that we developed,” Chou stated.

Reference: “Searching for Dark Matter with a Superconducting Qubit” by Akash V. Dixit, Srivatsan Chakram, Kevin He, Ankur Agrawal, Ravi K. Naik, David I. Schuster and Aaron Chou, 8 April 2021, Physical Review Letters.
DOI: 10.1103/PhysRevLett.126.141302

Funding: Heising-Simons Foundation, U.S. Department of Energy High-Energy Physics QuantISED program.