Researchers Develop Faster, Robust Gate for Quantum Computing Without Lasers

Researchers from the University of Siegen, the Hebrew University of Jerusalem, and the AWS Center for Quantum Computing have developed a novel two-qubit entangling gate for RF-controlled trapped-ion quantum processors. The new gate is faster, more robust, and does not require lasers, making it a significant advancement in quantum computing. It processes quantum information much faster and is less prone to errors. The gate requires only a single continuous RF field per qubit, making it easier to scale up the number of qubits in a quantum processor. This development could lead to the creation of practical, large-scale quantum computers.

What is the New Development in Quantum Computing?

A team of researchers from the Department of Physics, School of Science and Technology, University of Siegen, Germany, the Racah Institute of Physics, Hebrew University of Jerusalem, Israel, and the AWS Center for Quantum Computing, Pasadena, CA, USA, have proposed and demonstrated a novel two-qubit entangling gate for RF-controlled trapped-ion quantum processors. This new gate is faster, more robust, and does not require lasers, making it a significant advancement in the field of quantum computing.

The speed of this new gate is an order of magnitude higher than that of previously demonstrated two-qubit entangling gates in static magnetic field gradients. This means that it can process quantum information much faster, which is a crucial factor in the practical application of quantum computing. The researchers also found that the phase-modulated field driving the gate dynamically decouples the qubits from amplitude and frequency noise, increasing the qubits’ coherence time by two orders of magnitude. This makes the gate more robust and less prone to errors, another critical factor in quantum computing.

The gate requires only a single continuous RF field per qubit, making it well suited for scaling a quantum processor to large numbers of qubits. This is a significant advantage as one of the main challenges in quantum computing is scaling up the number of qubits while maintaining their coherence and control. The researchers were able to generate the Bell states with fidelities up to 98.23% in a static magnetic gradient of only 190.9 T/m. At higher magnetic field gradients, the entangling gate speed can be further improved to match that of laser-based counterparts.

How Does This New Gate Work?

The researchers used trapped atomic ions as a physical platform for quantum information processing. Trapped ions controlled by radio frequency (RF) signals are particularly suited for scaling up quantum computers since technological challenges associated with using laser light for coherent control of qubits are avoided in this laser-free approach. With RF-controlled ions, high fidelity single and two-qubit gates have been achieved, as well as low crosstalk suitable for fault-tolerant quantum computing.

The new two-qubit entangling gate takes advantage of a state-selective force induced by the static magnetic gradient field coupling the internal qubit states to the axial vibrational states of the 2-ion crystal. Therefore, when using magnetic gradient induced coupling (MAGIC), laser light is not required for implementing conditional gates with trapped ions. This is a significant advantage as lasers can introduce additional complexity and potential sources of error in quantum computing.

The ions are cooled close to their motional ground state in two stages. Initial Doppler cooling is followed by RF sideband cooling of both present vibrational modes, giving a mean phonon number of 0.65 in the center-of-mass (COM) mode. The heating rate of one trapped ion in the current experimental setup is 0.193 phonons/ms for this mode.

What is the Significance of This Development?

This development is significant because it addresses some of the main challenges in quantum computing, namely speed, robustness, and scalability. The new gate is faster than previous gates, which means it can process quantum information more quickly. It is also more robust, as it is less prone to errors due to amplitude and frequency noise. Finally, it is scalable, as it requires only a single continuous RF field per qubit, making it easier to increase the number of qubits in a quantum processor.

The researchers’ work also demonstrates the potential of RF-controlled trapped-ion quantum processors as a platform for quantum computing. This platform avoids the technological challenges associated with using laser light for coherent control of qubits, making it a promising approach for the development of practical, large-scale quantum computers.

The researchers’ work is a significant contribution to the field of quantum computing, and it opens up new possibilities for the development of faster, more robust, and scalable quantum processors. It also provides a solid foundation for further research and development in this exciting and rapidly evolving field.

What are the Future Implications of This Research?

The researchers’ work has several implications for the future of quantum computing. First, it demonstrates the feasibility of using RF-controlled trapped-ion quantum processors as a platform for quantum computing. This could lead to the development of practical, large-scale quantum computers that can solve problems beyond the reach of classical computers.

Second, the new gate’s speed, robustness, and scalability could make quantum computing more accessible and practical. Faster gate speeds mean that quantum computations can be completed more quickly, making quantum computers more useful for real-world applications. The gate’s robustness reduces the likelihood of errors, making quantum computations more reliable. And the gate’s scalability makes it easier to increase the number of qubits in a quantum processor, which is crucial for the development of large-scale quantum computers.

Finally, the researchers’ work could inspire further research and development in quantum computing. The novel two-qubit entangling gate they proposed and demonstrated could be used as a model for the development of other types of gates and quantum computing technologies. Their work could also lead to new insights into the physics of quantum computing, contributing to our understanding of this complex and fascinating field.

How Does This Research Contribute to the Field of Quantum Computing?

This research contributes to the field of quantum computing by proposing and demonstrating a novel two-qubit entangling gate for RF-controlled trapped-ion quantum processors. This new gate is faster, more robust, and does not require lasers, making it a significant advancement in the field.

The researchers’ work also contributes to our understanding of the physics of quantum computing. They demonstrated that the phase-modulated field driving the gate dynamically decouples the qubits from amplitude and frequency noise, increasing the qubits’ coherence time. This finding could lead to the development of more robust quantum computing technologies.

Finally, the researchers’ work contributes to the development of scalable quantum computing technologies. The new gate requires only a single continuous RF field per qubit, making it easier to increase the number of qubits in a quantum processor. This is a crucial factor in the development of practical, large-scale quantum computers.