Technological breakthrough! Scientists have realized the simultaneous operation of multiple semiconductor qubits for the first time

Quantum physicists at the University of Copenhagen reported an international achievement of Denmark in the field of quantum technology. By operating multiple spin qubits simultaneously on the same quantum chip, they overcome a key obstacle to the future practical quantum computer.

In the global marathon towards large quantum computers, an engineering problem is to control many qubits at the same time. This is because the control of one qubit is usually negatively affected by the synchronization control pulse applied to another qubit.

The advantage of spin qubit is that it can maintain its quantum state for a long time. This makes it possible for spin qubits to perform faster and more perfect calculations than other platforms. Moreover, the size of spin qubits is so small that more qubits can be compressed onto a chip than other qubit methods. The more quantum bits, the stronger the processing power of the computer. The team makes and operates 2 on a single chip × 2 array, which extends the existing technology.

So far, the biggest focus of quantum technology has been to manufacture better and better quantum bits. It's time for them to communicate with each other. Anasua Chatterjee said, "now we have some very good qubits. The most important thing is to connect them to a circuit that can operate many qubits. At the same time, it is complex enough to correct quantum computing errors. So far, the research on spin qubits has developed to the point that the circuit contains 2 × 2 or 3 × The problem is that others can only process one qubit at a time. "

In their quantum chip, four spin qubits are made of semiconductor material gallium arsenide, no larger than bacteria. Between the four qubits is a larger quantum dot, which connects the four qubits to each other. Researchers can use it to tune all qubits at the same time.
"The really innovative and important thing about our chip is that we can operate and measure all qubits at the same time. This has never been proved in spin qubits and many other types of qubits," said Chatterjee. The team's results were recently published in the journal Physical Review x quantum.

The realization of the new circuit is a milestone in the long road of semiconductor quantum computer. Professor kuemmeth, who directed the research, said: "in order to obtain a more powerful quantum processor, we should not only increase the number of qubits, but also increase the number of simultaneous operations, which is what we do."

At present, one of the main challenges they face is that the 48 control electrodes of the chip need to be manually tuned and continuously adjusted in the case of environmental drift, which is a cumbersome task for humans. At present, kuemmeth's research team is studying how to use optimization algorithm and machine learning to automatically tune. In order to manufacture larger quantum bit arrays, researchers have begun to work with industry partners to manufacture the next generation of quantum chips.

In general, the concerted efforts of computer science, microelectronics engineering and quantum physics may take spin qubits to the next milestone.

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