Physicists just made a breakthrough: quantum states that last over 5 seconds

And it could pave the way for a 'distributed quantum internet'.
Chris Young
Silicon carbide chip used in the researchDavid Awschalom / University of Chicago

Scientists made a breakthrough that could lead to more complex quantum calculations and even enable a "distributed quantum internet."

A team of researchers, from the U.S. Department of Energy's (DOE) Argonne National Laboratory and the University of Chicago, were able to maintain a quantum state intact for more than five seconds, a new record for the field of quantum science, a press statement reveals.

Extending quantum states to 'human timescales'

The team, who published their findings in the journal Science Advances, used a method called 'single shot readout' to easily read a qubit on demand. The method utilizes precise laser pulses to add single electrons to qubits, depending on their quantum state. This helped them to extend the qubits' quantum states for longer periods than ever before.

Maintaining quantum states for extended periods has been a notoriously difficult task in quantum science, as qubits easily lose their information due to environmental noise — this is one of the reasons quantum computers must operate at freezing temperatures. "It's uncommon to have quantum information preserved on these human timescales," said David Awschalom, senior scientist at Argonne National Laboratory.

"Five seconds is long enough to send a light-speed signal to the moon and back," Awschalom continued. "That's powerful if you're thinking about transmitting information from a qubit to someone via light. That light will still correctly reflect the qubit state even after it has circled the Earth almost 40 times — paving the way to make a distributed quantum internet."

Enough time to perform 100 million quantum operations

To reduce that infamous background noise, the researchers made their qubits out of highly purified silicon carbide samples, a material that is widely used in a commercial capacity, meaning it should be easy to scale up. By applying precise microwave pulses to their qubit, they extended the amount of time its preserved quantum information to over five seconds via a concept called "coherence".

"These pulses decouple the qubit from noise sources and errors by rapidly flipping the quantum state," said Chris Anderson of the University of Chicago, co-first author on the paper. "Each pulse is like hitting the undo button on our qubit, erasing any error that may have happened between pulses."

"We've essentially made a translator to convert from quantum states to the realm of electrons, which are the language of classical electronics, like what's in your smartphone," he continued. "We want to create a new generation of devices that are sensitive to single electrons, but that also host quantum states. Silicon carbide can do both, and that's why we think it really shines."

In theory, the researchers said the amount of quantum coherence they were able to achieve would allow them to perform over 100 million quantum operations. It's a breakthrough that could extend the capacity of quantum machines, allowing for more complex quantum computer operations and improved detection capabilities for future quantum sensors.

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