(ORDO NEWS) — Two atoms blown up to almost comical proportions and cooled to just above absolute zero have been used to create a robust, insanely fast two-qubit quantum gate that could help overcome some of the persistent problems of quantum computing.
Since the two-qubit gate is the fundamental building block of efficient quantum computers, this breakthrough is of great importance.
This could lead to a new type of quantum computer architecture that overcomes existing limitations for noiseless quantum operations.
A qubit is short for quantum bit. It is the quantum equivalent of an ordinary bit, the basic unit of information on which computing technology is based.
To solve a problem in the old fashioned way, the information (and the logic used to calculate it) is represented by a binary system.
Like a light switch, all the elements that make up this system are in an exclusive state: on or off. Or, as they are often described, as one or zero.
What makes quantum computing so much more powerful is that qubits can be in both states at the same time, in a state known as quantum superposition.
By itself, a qubit is not very similar to a computer. However, when combined (or entangled) with superpositions of other qubits, they can represent some very powerful algorithms.
A two-qubit gate is a logical operation based on the quantum state of two entangled qubits. This is the simplest component of a quantum computer that allows you to entangle and read qubits.
Scientists have been experimenting with quantum gates based on various materials for some time now and have made remarkable achievements.
However, one problem still remains significant: superpositions of qubits can quickly and easily degrade due to the fact that external sources also become entangled.
Speeding up the gate is the best way to solve this problem: since such an intrusion is typically slower than a millionth of a second (one microsecond), a faster quantum gate will be able to “outrun” the noise to perform accurate calculations.
To take on a slope in To achieve this goal, using a slightly different approach, a team of researchers led by physicist Yelai Chu of the National Institute of Natural Sciences in Japan turned to a complex setup.
The qubits themselves are rubidium metal atoms. in a gaseous state. With the help of lasers, these atoms were cooled to near absolute zero and placed at precise micron distances from each other using optical tweezers laser beams that can be used to manipulate atomic-scale objects.
Then, physicists affected the atoms with lasers. This knocked the electrons from the closest orbital distance to each atomic nucleus to a very large orbital distance, causing the atoms to swell into objects known as Rydberg atoms.
This produced a 6.5 nanosecond periodic exchange of orbital shape and electron energy between the now huge atoms.
By using more laser pulses, the research team was able to perform a quantum gate operation between two atoms.
The researchers said the speed of this operation was 6.5 billionths of a second (nanoseconds) more than 100 times faster than any previous Rydberg experiment setting a new record for quantum gates based on this particular technology.
This is not yet quite a record for the fastest operations of quantum gates with two qubits. This was achieved in 2019 using phosphorus atoms in silicon, reaching a mind-boggling 0.8 nanoseconds; but the new work includes a different approach that may circumvent some of the limitations of other types currently in development.
In addition, learning about different architectures can lead to clues that can help minimize weaknesses in other types of hardware.
The next steps, according to the team, are clear enough. They need to replace the commercial laser with a custom built one to improve accuracy, as the laser can contribute to noise; and implement better control methods.
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