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qubit states

Researchers discover superconductor that could enhance quantum computer development

Scientists at the National Institute of Standards and Technology (NIST) have discovered a superconductor that could very probably be useful for developing quantum computers by overcoming one of the main barriers in the development of effective quantum logic circuit. The paper has been published in Science journal.

Recently unearthed properties in the compound uranium ditelluride or UTe2 show that it could be highly resilient to one of the nemeses of quantum computer development – the problem with making memory storage switches of a quantum computer known as qubits, to function long enough to complete a calculation before losing the sensitive physical relationship that allows them to function as a group. This is known as quantum coherence which is difficult to sustain because of disturbances from the surrounding world.

It is one of the rare superconductor materials because of its peculiar and strong resistance to the magnetic field and provides benefits for qubit design, mainly their resistance to the fallacies that can easily drag into the quantum calculation. The research team’s Nick Butch said that UTe2’s unique properties could make it alluring to the emerging quantum computer sector.

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Butch, a physicist at the NIST Center for Neutron Research (NCNR) said that uranium ditelluride which is the silicon of the quantum information era could be used to build the qubits of an efficient quantum computer.

Results of research team which includes scientists from Ames Laboratory and the University of Maryland explain UTe2’s exceptional characteristics, interesting from viewpoint of both technical application and fundamental science.

Electrons that conduct electricity travel as separate particles in copper wire or some other ordinary conductor but in Superconductors, they form cooper pairs and the electromagnetic interactions that produce these pairings are responsible for the material’s superconductivity. BCS theory which explains this type of superconductivity is named after the three scientists who revealed the pairings and also won the Nobel prize for that.

The property of electrons that is especially important to the cooper pairing is the quantum “spin” that makes electrons act as if they have a little bar magnet running through them. In the majority of superconductors, the paired electrons have their quantum spins oriented one upward and other downwards and the opposed pairing is called a spin-singlet.

The Cooper pairs in UTe2 can have their spins oriented in one of three combinations making their spin triplets oriented in parallel rather than opposition making it nonconformists like the very few known superconductors. Most of the spin-triplet SCs are assumed to be “topological” with an extremely useful quality in which the superconductivity occurs on the material’s surface and persist even in the presence of outer shocks.

These parallel spin pairs could help the computer keep operative and can’t automatically collapse because of quantum variations. Superconductor has been perceived to have advantages as the basis for quantum computer elements, and recent economical advances in quantum computer development have engaged circuits made from superconductors, unlike the quantum computer that need a way to correct the errors that drag in from their surroundings because of the topological SC’s properties.

Butch said that Topological superconductors are a substitute path to quantum computing because of long lifespan and it gives error-free qubits and also protects it from the environment.

Researchers stumbled upon UTe2 while exploring uranium-based magnets whose electronic properties can be adjusted as desired by changing their chemistry, pressure or magnetic field and is a useful feature for customizable materials (the material consists of slightly radioactive “depleted uranium”).

UTe2 was first developed back in the 1970s but recently while making some UTe2 while they were synthesizing related materials, they experimented it at lower temperatures to see if any event might have been ignored and they noticed that they had something very special.

The NIST team at both the NCNR and the University of Maryland started studying UTe2 with specialized tools and noticed that it became superconducting at low temperatures (below -271.5 oCelsius, or 1.6 Kelvin) with properties resembling rare ferromagnetic superconductors which acts like low-temperature permanent magnets. Yet, strangely UTe2 is itself not ferromagnetic which makes it fundamentally new.

UTe2 can resist fields as high as 35 Tesla which is 3,500 times strong as a normal refrigerator magnet, and much more than the lowest temperature topological SCs can resist.

This extraordinary resistance to strong magnetic fields means it is a spin-triplet SC and likely a topological SC as well and will help researchers to study the nature of UTe2 and superconductivity itself. The main purpose of this research and exploring SC’s is to study superconductivity and to know where to look for undiscovered SC materials which is difficult right now and also to understand what stabilizes these parallel-spin SCs.

Journal Reference: Science journal

About the author: Kalpit Veerwal
Kalpit Veerwal is a second year Computer Science undergraduate at IIT Bombay. He is well known for being the only person to score 360/360 in JEE (Main). He is registered in the Limca Book of Records for the same. A blogger in his free time, he has also secured top ranks in various exams held in India and the world.

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