What is quantum mechanics?
Quantum Interference: particles that move like waves
The central concept of quantum physics is that everything comes in small chunks, or quanta. At the scales where quantum mechanics is important, roughly the size of an atom - less than a billionth of a meter, this “chunkiness” radically changes the way matter and energy move and interact with each other.
For one thing, quantum particles move like waves. This applies not just to the particles of light (photons), which are pure energy, but also to massive particles such as electons, neutrons and protons. Its amazing but true: every particle moves like a wave. This waviness allows for something really interesting to happen: waves can add and subtract, allowing them to interfere, much like light waves or sound waves.
In quantum mechanics the waves encode information about the probability of the particle being at different locations. The fact that waves interefere leads to the possibility of quantum superposition, whereby a particle behavies as if it was in two places at the same time.
Even more alarmingly, quantum mechanics allows widely separated particles to somehow communicate with each other. Einstein called this Quantum Entanglement “spooky action at a distance”. No one knows quite how this communication works, and it remains one of the great mysteries of nature.
These bizzare quantum features have inspired scientists to invent quantum computers, quantum cryptography, and the field of quantum information. Instead of using a binary bit of information, encoding true or false as 1 or 0, quantum information uses a qubit, a quantum superposition of 1 and 0, to encode more information. This allows for a radical rethink of the scope of computing, allowing for massively parallel problems to be tackled in a new way.
A central goal in quantum computing is the reliable storage and retrieval of quantum information. Work at Otago has helped to develop high quality quantum memory, akin to a quantum hard drive. To find out more, visit the Quantum Optics Research Group.
Quantum Entanglement: spooky action at a distance
Quantum computers bring new capabilites
The Centre for Quantum Science is a University of Otago Research Centre hosted by the Department of Physics.
ashton.bradley [at] otago.ac.nz
niels.kjaergaard [at] otago.ac.nz