Quantum Technologies exploit the quantum mechanical behaviour of atoms, structures, light and their interactions. While this could encompass phenomena and devices from lasers and semiconductors to superconductors and photon-counting detectors, in the current context it particularly refers to effects such as superposition, interference and entanglement that rely upon the coherence of the quantum wavefunction rather than randomized averages.

Quantum mechanics describes all objects, particles and fields in terms of wavefunctions, and quantum technologies rely upon the manipulation and measurement of these wavefunctions. Quantization refers to the way that measurements of a quantity can result in only certain values, with probabilities determined by the wavefunction. This allows a second feature of quantum technologies – that microscopic systems can be absolutely identical, eliminating the variations that with larger systems occur from one instance to another.

While the theory of the ‘mechanics’ of quantum systems – as described by the Schrödinger and Dirac equations – has been confirmed to a precision of parts in 10¹⁵, there is no theory for the mechanics of a quantum measurement, and the ‘spooky action at a distance’ that perplexed Alfred Einstein remains a puzzle. Happily, our understanding of the mechanics is more than enough to understand the phenomena behind quantum technologies for sensing, timing, imaging, computing and communication.

Quantum Technology is about exploiting quantum mechanics for practical applications: making computers more powerful by intrinsically parallel processing; making inertial and external field sensors (acceleration, rotation, gravity, gravity gradient, magnetic field, electromagnetic field) more sensitive and stable; putting miniature atomic clocks into every cellphone base station and even every phone and vehicle for improved navigation and bandwidth; providing long-distance encrypted communications that can’t be intercepted without alerting the users.

Making these Quantum Technologies a practical reality requires not only a knowledge and understanding of quantum mechanical phenomena but the design and construction of quantum components, development of fabrication techniques and processes, assembly to form devices and systems, protocol and software development, practical trials and evaluation, and engineering for a range of user applications. The EPSRC CDT in Quantum Technology Engineering draws upon Southampton’s Schools of Physics & Astronomy, Chemistry, Electronics & Computer Science and Engineering, Optoelectronics Research Centre, Institute of Sound & Vibration Research and National Oceanography Centre Southampton to provide research and training across all these areas of expertise.