I've been on a smartphone-photonics kick lately, and I haven't stopped yet. I've discovered that quantum key distribution (QKD), a fundamentally quantum-mechanical way of securely communicating information, may one day be coming to your iPhone (or Android phone, of course).
A group of UK, Chinese, and Australian researchers has developed a telecom-fiber tethered QKD system that allows a mobile phone with a built-in on-chip polarization rotator to be plugged in via optical fiber to a computer such that supremely secure quantum-mechanical qubits are the means of transmitting a cryptographic key. After this supposedly completely secure transfer, the user unplugs his/her phone and walks away (with the phone, of course).
The research was led by scientists at the Centre for Quantum Photonics, located at the University of Bristol (Bristol, England); for more info, see P. Zhang et al., Physical Review Letters (2014); doi: http://dx.doi.org/10.1103/PhysRevLett.112.130501
By the way, the Centre for Quantum Photonics has also made an authentic quantum computer called "Quantum in the Cloud" accessible to the public online. See http://www.bristol.ac.uk/physics/research/quantum/qcloud/
