Researchers from the University of Basel and the NCCR SPIN have achieved a significant breakthrough by successfully demonstrating the first controllable interaction between two hole spin qubits in a conventional silicon transistor. This achievement opens up the possibility of integrating millions of qubits on a single chip using mature manufacturing processes. The development of practical quantum computers is a priority for researchers worldwide, and the choice of qubit technology plays a crucial role in maximizing the potential of quantum information science.
Qubits are the fundamental building blocks of a quantum computer, responsible for processing, transferring, and storing data. For a quantum computer to function effectively, qubits must be able to reliably store and rapidly process information. The key to rapid information processing lies in stable and fast interactions between numerous qubits whose states can be controlled externally. Current quantum computers only have a few hundred qubits, limiting their ability to perform complex calculations beyond the capabilities of conventional computers.
To address the challenge of accommodating and connecting thousands of qubits on a single chip, researchers at the University of Basel and the NCCR SPIN are focusing on qubits that use the spin of an electron or a hole. Both holes and electrons possess spin, which can be controlled electrically. In previous research, hole spins in existing electronic devices, such as FinFETs, were successfully trapped and used as qubits. The recent achievement of a controlled interaction between two qubits within this setup marks a significant advancement in quantum computing.
In their study published in Nature Physics, the researchers were able to couple two qubits and achieve a controlled spin-flip based on the state of the other qubit. This controlled spin-flip is essential for performing calculations on a quantum computer. The exchange interaction between the two spin qubits, which is electrostatic in nature, plays a crucial role in their coupling. The anisotropic nature of the exchange energy of holes, influenced by spin-orbit coupling, enables fast and high-fidelity two-qubit gates without compromising on speed or accuracy.
The use of hole spins as qubits offers several advantages, including the utilization of existing silicon chip fabrication processes, scalability, and robustness in experiments. The researchers believe that qubits based on hole spins have the potential to drive the development of large-scale quantum computers. This novel approach provides a promising pathway towards achieving the goal of integrating millions of qubits on a single chip, a critical milestone in advancing quantum information science and technology.
