Australian scientists have increased qubit stability 10 times

A team of Australian researchers from the University of New South Wales ( UNSW ) developed a qubit that remains in stable superposition 10 times longer than previous designs. Scientists believe that their new qubit can significantly increase the reliability of quantum computing. The results of the study were published in the journal Nature Nanotechnology on October 17, 2016.

Qbits (quantum bits) can take the value 0 and 1, as well as the standard bits, but at the same time go into a state of superposition at any change of state. New technology developed in UNSW, called "dressed" qubit. This is no accident: such a qubit is the spin of a single silicon atom surrounded by an electromagnetic field. This property allows the quantum bit to keep information about the quantum longer than the "not dressed" atom.
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The “dressed” quantum bit is not the first achievement of UNSW in the field of quantum computing: the team has already created the longest-lived qubit in the solid state. This was made possible by coding quantum information into the spin of a single phosphorus atom in a silicon crystal placed in a static magnetic field.

Now scientists have implemented a new way of coding information. They subjected the atom to a very strong, constantly oscillating electromagnetic field in the range of ultrahigh frequencies. The results were astounding: since the field oscillates continuously at high frequency, any noise or interference at different frequencies is mutually subtracted and reduced to zero. Researchers have achieved a result in which the state of superposition can be held 10 times longer than before.

All previous qubits were fragile and short-lived. The preservation of superposition over time has become one of the main obstacles to the development of quantum computing. However, the research team was able to extend this state to 2.4 milliseconds. During this time, you can perform a lot more operations than before. At the same time, the time interval during which information is securely stored has increased. Scientists note that such a result could not be achieved with the "not dressed" quantum bit.


Along with information on expanding the time frame for superposition, the researchers also reported that a “dressed qubit” provides for greater bandwidth for various manipulations. A “dressed” qubit, unlike a “not dressed” one, is controlled in various ways. Andrea Morello, head of the UNSW research team, suggests that you can control the quantum bit by modulating the frequency of the microwave field, like FM radio. A “not dressed” qubit, in turn, requires switching the amplitude of the field, like AM radio.

Perhaps that is why a qubit surrounded by a magnetic field is more resistant to noise. Quantum information is controlled by a frequency that is constant, while the amplitude can be affected by external noise. Since the device is built on standard silicon technology, it can be used to create powerful and reliable quantum processors. Production stages will not differ from that used for modern computers.

“Dressed” quantum bits are more versatile and durable than a single electron, and this will allow us to create more reliable quantum computers, ”notes Arne Löcht. Today, the UNSW team is the world leader in silicon-based quantum computing. With the participation of Morello, the team managed to get $ 70 million Australian dollars ($ 53.5 million) from researchers, businessmen and the Australian government. This amount will be spent on creating a prototype of a silicon quantum integrated circuit - the first step in the construction of a quantum computer.

Creating a quantum computer is often called the “space race of the 21st century”. In theory, this machine can be a revolutionary tool for computing that no other device can produce. In a conventional computer, all information is represented as 0 and 1, while quantum information can combine both options at the same time. Everything happens right away, and you don’t have to go through a long list of options, which is what the “classic” devices actually do. In a number of key areas: searching for information in large and unsorted databases, solving complex systems of equations and creating drugs, a quantum computer will simply not be equal.

Quantum computers could quickly develop drugs by accelerating the work of computer-aided design of pharmaceutical compounds and reducing the time for tests. In addition, you can design new, lighter and more durable materials in all areas of production, from consumer electronics to aircraft construction.

The first quantum computer , created in 1998, could control a single qubit, while among modern ones this figure does not exceed 16. The scientists predict that in order for a computer to solve its tasks, the minimum number of qubits should exceed two dozen. A few years ago, D-Wave tried to create a processor with 84 quantum bits, but experts criticized it, saying that it works in the same way as a regular chip. Now MIT scientists are working on creating a prototype chip that is able to “lure” ions into an electric field trap and control them using laser technology.

All this pushes to the conclusion that while quantum computers are far from practical application. However, their actual potential is undeniable. One day, a computer can quickly and easily perform calculations that take an awful lot of time on classic devices. Already, they pose a threat to asymmetric cryptography.