Finnish researchers at Aalto University have made a significant advancement in quantum computing. The team achieved a new scientific record for transmon qubit coherence time, a key performance metric in quantum computing.
Specifically, they achieved an echo coherence time of 1 millisecond for a transmon qubit, with a median of 0.5 milliseconds. This crushes previous records of around 0.6 milliseconds.
For those who are not aware, coherence time refers to the duration during which a qubit can maintain its quantum state without errors due to environmental noise. In other words, the qubits can remain in a fragile quantum state (also known as superposition) for longer before decohering.
When this happens, the qubit loses all its quantum information. Therefore, longer coherence times equate to more time to perform complex operations without losing fidelity.
Longer coherence = better quantum computing
It also reduces the need for heavy quantum error correction, which is crucial for scaling up to practical, fault-tolerant quantum computers. Simply put, the longer this time, in theory at least, the more usable a quantum computer becomes.
“Quantum computers are [on] the verge of becoming useful with the increasing qubit coherence and fidelity. The first applications seem to lie in solving hard but short mathematical problems, such as high-order binary optimization problems,” Mikko Möttönen, Professor of Quantum Technology at Aalto University, told IE.
To achieve this incredible feat, the team built high-quality transmon qubits in cleanroom facilities at Aalto University. The required superconducting materials came from VTT, Finland’s national research institute.
They utilized Micronova cleanrooms, a component of Finland’s OtaNano infrastructure. The setup was led by Ph.D. student Mikko Tuokkola and supervised by Dr. Yoshiki Sunada (now at Stanford).
“At the moment, quantum error correction is only moderately improving qubit coherence because of still too frequent errors on the physical qubits. Thus, several factor-of-two improvements are required for efficient quantum error correction, and these first ones provide the most advantage in terms of the required number of physical qubits,” Möttönen explained to IE.
The achievement is not just a significant win for the team, but also for Finland as a whole. It can, in part, help Finland position itself as a global leader in quantum technology.
Quantum computers within five years?
The work is also supported by major initiatives, including the Finnish Quantum Flagship (FQF) and the Academy of Finland’s Centre of Excellence in Quantum Technology. Aalto’s Quantum Computing and Devices group is opening new positions to accelerate future breakthroughs.
“This landmark achievement has strengthened Finland’s standing as a global leader in the field, moving the needle forward on what can be made possible with the quantum computers of the future,” Möttönen explained.
Looking ahead, achievements like this are edging us closer to real-world applications of quantum computers, perhaps even within the next five to ten years.
“It appears to me that industrial and commercial use of this technology is likely within the next five years, first in the form of early NISQ algorithms and then in the lightly error-corrected machines,” he said.