A team of physicists at Max-Planck-Institute of Quantum
Optics, Harvard University, and California Institute of Technology develops a
scheme for noise tolerant and yet safely encrypted quantum tokens.
Whoever has paid a hotel bill by credit card knows about the
pending danger: given away the numbers of the card, the bank account and so on,
an adversary might be able to forge a duplicate, take all the money from the
account and ruin the person. On the other hand, as first acknowledged by
Stephen Wiesner in 1983, nature provides ways to prevent forging: it is, for
example, impossible to clone quantum information which is stored on a qubit. So
why not use these features for the safe verification of quantum money? While
the digits printed on a credit card are quite robust to the usual wear and tear
of normal use in a wallet, its quantum information counterparts are generally
quite challenged by noise, decoherence and operational imperfections.
journal reference (abstract free): pnas >>