Record-breaking quantum computer with more than 1,000 qubits

US company Atom Computing creates the first quantum computer with 1,180 qubits, which can improve the machine's accuracy.

The largest quantum computer built by Atom Computing. Photo: Atom Computing — The largest quantum computer built by Atom Computing. Photo: *Atom Computing*

The world's first quantum computer has more than twice as many quantum bits (qubits) as the previous world record holder, IBM's Osprey (433 qubits). While more qubits doesn't necessarily mean better performance, a large number of qubits is essential for future error-free quantum computers, unlike today's noisy research machines. The largest quantum computers, such as those from IBM and Google, use superconducting circuits cooled to extremely low temperatures. But the record-breaking machine from California startup Atom Computing has 1,180 qubits, using neutral atoms held in place by lasers in a two-dimensional lattice, New Scientist reported on October 24.

One advantage of this design is that it is easy to scale the system and add more qubits to the network, according to Rob Hays, CEO of Atom Computing. Any useful future quantum computer that is error-free (a property called fault tolerance) will need at least tens of thousands of error-correcting qubits operating in parallel with the programming qubit.

“If we just scale up to tens of qubits, like most superconducting and ion-trap systems do today, it will take a very long time to get to the era of fault-tolerant machines. With the neutral atom approach, we can get there much faster,” Hays explains. According to him, the Atom Computing team aims to increase the number of qubits in the machine by a factor of about 10 every two years.

Unlike conventional computer bits, which are either 1 or 0, qubits are more diverse, with a range of different characteristics depending on how they are made. Neutral atoms are better suited to quantum entanglement, a strange quantum effect in which two qubits are linked and can influence each other even over vast distances. They are also more stable. The qubit in Atom Computing's computer prevents the quantum state from collapsing, thus achieving fault tolerance, for nearly a minute. By comparison, IBM's Osprey computer has a qubit binding time of just 70 to 80 microseconds.

The long coherence time comes from the ytterbium atom that Hays and his colleagues used as a qubit. Most neutral-atom machines use the atom’s electrons as quantum elements to perform calculations, but they are easily disturbed by the powerful lasers used to hold them in place. With ytterbium, the researchers were able to take advantage of a quantum feature of the atom’s nucleus called spin (the particle’s intrinsic angular momentum), which is less susceptible to disturbance. According to Atom Computing researcher Ben Bloom, the nucleus does not interact with its external environment as strongly as the electron.

Because qubits have so many different characteristics, it is difficult to compare them between different machines. However, Bloom said Atom Computing's machine has the same processing power as IBM's computer. The team hopes to make the computer available to customers next year for cloud computing applications.

An Khang (According to New Scientist )

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