Glossary on quantum technologies
Post-quantum cryptography
Post-quantum cryptography refers to encryption methods that, unlike current methods, are resistant to attacks by quantum computers.
Quanta
Smallest discrete units out of which physical object, e.g. matter and energy, are composed. Quanta behave differently from classical objects in the everyday world; for example, they have both wave and particle properties.
Quantum computer
A computer that is based on the principles of quantum mechanics and uses qubits instead of bits. It has the potential to solve complex problems much faster than conventional computers. Quantum computers are still under development, but they can trigger a revolution in many areas of science and technology.
Quantum interference
The superimposed states of a quantum system can interfere with each other in a similar way to water waves. This leads to amplifications or cancellations of the probabilities with which individual states of the system are measured.
Quantum internet
The quantum internet is a hypothetical network based on quantum mechanical principles that can transmit data over long distances without being intercepted. It could also connect quantum computers worldwide.
Quantum mechanics
Mathematical description of quantum physics. Alongside the theory of relativity, quantum mechanics is one of the pillars of modern physics.
Quantum physics
Quantum physics is a branch of physics that deals with the behavior and properties of quanta. It describes phenomena at the atomic and subatomic level that cannot be explained using the rules of classical physics.
Quantum sensors
Quantum sensors are measuring instruments that use quantum mechanical principles to carry out extremely precise measurements. For example, they can detect magnetic fields, temperature or other physical quantities.
Quantum system
A quantum system is a physical entity that is described according to the laws of quantum mechanics. It can consist of particles, atoms, molecules or other quantum mechanical objects.
Qubits
Qubits are the basic units of information in a quantum computer. In contrast to classical bits, which can only have the state 0 or 1, qubits can exist in a superposition of states.
Superposition
The properties of quantum objects are not defined independent of their measurement. If a particle is in a superposition of two states, measuring its state will give a random result. Still, in the absence of a measurement, the state of the system is well-defined and can be controlled. Superposition states are very sensitive to perturbations, which makes them a valuable resource for quantum sensing. In addition, they may be used to encode information in a way that is proof against eavesdropping. Finally, superposition states may be used in computations to increase the amount of information that a quantum system can process.
Entanglement
The inseparable connection of two or more quantum systems that continue to influence each other even when they are far apart. Entanglement is a unique property of quantum systems that cannot be achieved with classical devices. Its counterintuitive properties thus lay the foundation for all quantum technologies.