What is quantum technology?

Quantum technology is a new field of physics and engineering, which exploits the distinctive features of quantum mechanics, especially entanglement, for the development of enhanced practical applications such as quantum metrology, quantum cryptography, quantum interferometry, quantum imaging, and quantum computing. The field of quantum technology is born under the the influx of new ideas from the field of quantum information processing, and currently involves implementations in different area of physics, in particular quantum optics, atom optics, and nanomechanical devices.

What is quantum information?

Quantum information is a new field of science which draws upon the disciplines of physics, mathematics, computer science, and engineering. Its aim is to understand how fundamental physical laws can be harnessed to improve the acquisition, transmission and processing of information.

The starting of quantum information is the discovery that quantum mechanics can be exploited to perform important and otherwise intractable information processing tasks. Quantum effects have already been used to create fundamentally unbreakable cryptographic codes, to teleport the full quantum state of a light beam, and to compute certain function in fewer steps than and classical computer can.

Information is always encoded in a state of a physical system, whose evolution is ultimately governed by quantum mechanics.

What is quantum computing?

A quantum computer is based on the idea of a quantum bit or qubit. In classical computers, a bit is discrete and can represent either a “0” or a “1” state. A qubit can be in a linear superposition of the two states.

Hence, when a qubit is measured the result will be “0” or “1” with a certain probabilities. A quantum register consists of n qubits. Because of superposition, a phenomenon know as quantum parallelism allows exponentially many computations to take place simultaneously, thus vastly increasing the speed of computation.

A quantum computer would to be able to factor and compute discrete logarithms in polynomial time. Unfortunately, the development of a practical quantum computer seems, for the moment, far away because of the decoherence due to the influence of the outside environment.

What is Quantum Optics ?

Quantum Optics studies the generation, manipulation and characterization of quantum states of light as well as the quantum mechanical aspects of the interaction among light and atoms.

Quantum Optics was born with the advent of the laser (1960); in fact using intense optical beams one can see nonlinear optical effects which would otherwise be negligible with conventional light. These effects has been used to produce nonclassical light and to careful control interactions with atoms. Quantum Optics offers the opportunity of manipulation single atoms and photons, controlling their interaction on a quantum level with minimum decoherence. Quantum Optics is also important in communication technology, e. g. in optical fibers, since the quantum uncertainty is the main source of noise.

Why Quantum Optics ?

Photons are quite easily produced and manipulated. The electromagnetic environment at optical frequencies is substantially the vacuum (the indetermination of single optical photon is equivalent to 10000 Kelvin of thermal noise) and thus docoherence is small compared to material systems. Generation of nonclassical and entangled states of light is the realm of quantum optics labs.

Indeed quantum optics continues to play a major role in testing fundamental properties of quantum mechanics. As a matter of fact, the effective implementations of high precision measurements and quantum information protocols, such teleportation, dense coding and cryptography have been obtained using light beams.

Quantum Technology Lab – Dipartimento di Fisica – Università degli Studi di Milano