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Quantum researchers create a bug-correcting cat



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Yale physicists have developed a bug-correcting cat – a new device that combines Schrödinger’s cat superposition concept (a physical system that exists in two states at the same time) with the ability to fix one. number of the most difficult errors in quantum computing.

This is Yale̵

7;s latest breakthrough in an attempt to master and manipulate the physics required for a useful quantum computer: Correcting the error stream that occurs between bits of fragile quantum information, known as qubits, while on a mission.

A new study reporting on this discovery appeared in the journal nature. The lead author is Michel Devoret, Professor of Physics and Applied Physics FW Beinecke of Yale. The study’s first co-authors were Alexander Grimm, a former postdoctoral associate in Devoret’s lab who is currently a longtime scientist at the Paul Scherrer Institute in Switzerland, and Nicholas Frattini, a study. was born in Devoret’s laboratory.

Quantum computing has the potential to transform a wide range of industries, from pharmaceuticals to financial services, by enabling faster computation than today’s supercomputers.

Yale – led by Devoret, Robert Schoelkopf and Steven Girvin – continues to build on two decades of groundbreaking quantum research. Yale’s method of building a quantum computer is called a “QED circuit” and uses particles of microwave light (photons) in a superconducting microwave resonator.

In traditional computers, the information is encoded as either 0 or 1. The only error that appears during the computation is “bit-flips”, when a bit of information accidentally changes from 0 to 1 or vice versa. The way to fix the error is to build redundancy: uses three “physical” bits of information to ensure an “efficient” —or correct — bit.

In contrast, quantum information bits – qubits – suffer both bit inversion and “phase reversal”, where a qubit randomly reverses between the quantum superposition positions (when two opposite states coexist time).

So far, quantum researchers have been trying to correct the error by replenishing larger amounts, requiring ample physical qubits for each effective qubit.

Enter a cat qubit – named for Schrödinger’s cat, the famous paradox used to illustrate the concept of piling.

The idea is that a cat is placed in a closed container with the source of radioactivity and the poison will be activated if one atom of the radioactive material decomposes. The superposition theory of quantum physics holds that until someone opens the box, the cat is both alive and dead, a superposition of states. Opening the box to observe the cat causes it to randomly change its quantum state, forcing it to live or die.

“Our work is rooted in a new idea. Why not use an intelligent way to encode information in a single physical system so that one type of error is directly suppressed?” Devoret asked.

Unlike many of the physical qubits required to maintain an efficient qubit, a single cat qubit can prevent phase reversal on its own. A cat qubit encodes an effective qubit into superposition states of two states in an electronic circuit – in this case a superconducting microwave resonator whose vibrations correspond to the two states of a cat qubit.

“We achieve all of this by applying microwave-frequency signals to a device that is not significantly more complex than the traditional superconducting qubit,” Grimm said.

The researchers say they can change the cat’s qubit from any of its superposition states to any other, according to the command. Additionally, researchers have developed a new way to read out – or identify – information encoded into qubits.

“This makes the system on which we have developed a flexible new element, which will hopefully be used in many aspects of quantum computing with superconducting circuits,” Devoret said.


The new device extends the life span of quantum information


More information:
A. Grimm et al, Stability and activity of the qubit Kerr-cat, nature (Year 2020). DOI: 10.1038 / s41586-020-2587-z

Provided by Yale University



Quote: Quantum researchers create a bug-correcting cat (2020, August 12) retrieved August 12, 2020 from https://phys.org/news/2020-08-quantum-error- correcting-cat.html

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