Researchers at the University of Waterloo’s Institute for Quantum Computing (IQC) have developed a new wiring and connectivity technology that can be used to realize control of superconducting quantum bits, qubits. And this technology, in conjunction with several other technologies, is a significant step toward the development of scalable quantum computers.
In order to be able to control the quantum state of superconducting qubits, pulses of microwave radiation that are produced by specialized generators are typically used. These generators are connected to the cryostats, which hold the qubits at cryogenic temperature, by a complex network of high-frequency cables. It is the complexity of this system, plus the need to ensure its operation at both normal and cryogenic temperatures, served as an obstacle to the further development of this area of quantum computing.
“The quantum socket we have developed, a connection method that uses spring contact conductors, can provide control for each individual qubit of a quantum computer,” says Jeremy Bejanin, a University of Waterloo scientist. “This technology allows classical electronics to be combined with quantum circuits. It is scalable down to the level of several thousand qubits on a single quantum processor chip.
The device created by scientists functions effectively at cryogenic temperatures and at high frequencies up to 10 GHz, which is required for quantum computers with superconducting qubits. In addition, this connection method can be used to control the so-called “super-qubit,” a matrix of several hundred qubits that work as one large logical qubit, reducing the error rate by one or two orders of magnitude. An existing quantum socket can provide control of a matrix of 105 by 105 qubits, giving a quantum computer enough power to solve the most complex problems in physics, chemistry and astronomy that cannot be solved with traditional computers.
“All of the current-carrying elements of our quantum socket are designed to operate at ultra-low temperatures and they have all the necessary characteristics to operate in the microwave range, which is used to control superconducting qubits,” says Matteo Mariantoni, professor at the University of Waterloo, “Our device capabilities enable the control of superconducting quantum devices, and this is one of the critical steps needed to build scalable quantum computing systems.”
