Technology / What is Quantum Computing?

Quantum computers are devices that utilize the principles of quantum mechanics, such as quantum superposition. By harnessing these principles, they can solve some critical industry issues that are impossible to solve even with supercomputers.

Classical computing /
Classical Bit
A state that is either 0 or 1
Quantum computing /
Quantum Bit
Describing 0 and 1 at the same time through superposition
Classical computing / Classical Bit
Three bits describes only one of eight states
Quantum computing / Quantum BIT
Three qubits describes eight states at the same time

Quantum computers make good use of superposition states.

Types of quantum computers

Type Initiative companies Diagram Commentary
Superconductivity Google AI Quantum, IBM, Rigetti Computing, Quantum Circuits, AWS, Alibaba, Yale University, TU Delft, RIKEN Charges and magnetic fluxes in tiny electric circuits containing Josephson junction elements made of superconductors are used as qubits. Microwaves are used to operate quantum gates.
Ion trap Honeywell, IonQ, AQT, Osaka University (Toyoda Group) The electronic states of atomic ions trapped in a vacuum using an electric field are used as qubits. Quantum gate operations are performed using laser light.
Photon PsiQuantum, Xanadu, University of Science and Technology of China, The University of Tokyo (Furusawa & Yoshikawa group) Polarization modes (longitudinal and transverse polarization) of a single photon can be used as qubits. Quantum gate operations are performed using optical crystals and waveguides.
Silicon Intel, SeeQC, RIKEN Electron spins trapped in a region called a quantum dot on a silicon substrate are used as qubits. Quantum gate operation is performed by controlling electromagnetic waves and voltage on the substrate.

Hardware development of quantum computers is taking place around the world. Although all hardware has in common the use of quantum superposition and quantum entanglement, their physical realization methods differ, resulting in differences in computational accuracy and the operations they are good at.

The potential of quantum computers

Many applications for quantum computers are being considered, including chemical calculations, machine learning, and financial simulation.
However, these range from applications that may be realized within a few years to those that will take a decade or more, with varying degrees of impact expected at the moment.

Using Quantum algorithms, industrial applications can be translated into sets of quantum computational operations, described by quantum circuits.
Quantum circuits can be run on any type of universal quantum computing hardware by being converted, or compiled, for the specific gate set supported by the hardware.
Developing quantum algorithm is essential for preparing to take advantage of practical quantum hardware when it becomes available. QunaSys is developing various quantum algorithms and compilers for use in the quantum computers in the future.