• Wed. Nov 29th, 2023

    Critical Thought

    Critical thoughts on quantum technologies

    A Promising Breakthrough in Quantum Computing Manipulation

    BySam Figg

    Nov 21, 2023
    A Promising Breakthrough in Quantum Computing Manipulation

    Researchers at the Institute for Quantum Computing (IQC) at the University of Waterloo have recently achieved a significant breakthrough in the manipulation of individual qubits composed of barium using laser light. This groundbreaking method is a major step forward in the pursuit of functional quantum computers.

    The key to this new technique lies in the utilization of a small glass waveguide. By separating laser beams and precisely focusing them with a separation of four microns, the researchers have achieved unparalleled precision and simultaneous control over each focused laser beam on its target qubit. Unlike previous methods, this approach does not result in any interference between the laser beams, allowing for greater flexibility and control.

    “This is the most flexible ion qubit control system with this high precision that we know of anywhere, in academia and industry,” said Dr. K. Rajibul Islam, a professor at IQC and Waterloo’s Department of Physics and Astronomy.

    By focusing their attention on barium ions, the researchers have tapped into the advantageous energy states that make them suitable for qubit manipulation. Unlike other atom types that require higher energy ultraviolet light, barium ions can be manipulated using visible green light. This distinction enables the researchers to leverage commercially accessible optical technologies that were previously not feasible for ultraviolet wavelengths.

    To achieve the desired close spacing of the laser beams, the research team developed a waveguide chip that splits a single laser beam into 16 distinct light channels. These channels are then routed into individual modulators based on optical fibers. These modulators offer independent and agile control over various aspects of each laser beam, such as intensity, frequency, and phase.

    The future looks promising for this new waveguide approach. It provides a straightforward and highly accurate means of control, opening up possibilities for encoding and processing quantum data. It also holds significant potential for applications in quantum simulation and computing.


    1. What is a qubit?

    A qubit, short for quantum bit, is the fundamental unit of information in quantum computing. It is the quantum analog of the classical bit and can represent both a 0 and a 1 simultaneously, thanks to the principle of superposition.

    2. How does laser light manipulate qubits?

    Laser light can manipulate qubits by interacting with the atoms or ions that make up the qubits. Through precise control of the laser’s intensity, frequency, and phase, researchers can influence the energy states of the qubits, enabling operations and computations.

    3. What are the advantages of barium ions for qubit manipulation?

    Barium ions have advantageous energy states that make them suitable for qubit manipulation. Unlike other atom types, they can be manipulated using visible green light, which allows for the utilization of commercially accessible optical technologies.

    4. What is the significance of the waveguide approach?

    The waveguide approach offers unparalleled precision and simultaneous control over individual qubits. It allows for precise focusing of laser beams with a separation of a few microns, enabling agile and independent control over each beam. This approach holds great promise for manipulating ions to encode and process quantum data.

    (Sources: University of Waterloo)