All to do with a cat who may or
may not be alive
Physicists at the National Institute of
Standards and Technology (NIST) come up with a viable way to manipulate a
single "bit" in a quantum processor without disturbing the information
stored in its neighbours.
Apparently this was a hurdle in developing quantum
computers and the boffins have got around it by using polarised light to
create "effective" magnetic fields. Quantum bits, or "qubits," have the
uncanny ability to exist in both "on" and "off" positions simultaneously.
This makes them powerful when it comes to finding out the answers to
problems conventional computers
find impossible.
One approach to quantum
computer development aims to use a single isolated rubidium atom as a qubit.
Each such rubidium atom can take on any of eight different energy states, so
the design goal is to choose two of these energy states to represent the on
and off positions. Ideally, these two states should be completely
insensitive to stray magnetic fields that can destroy the qubit's ability to
be simultaneously on and off, ruining calculations. However, choosing such
"field-insensitive" states also makes the qubits less sensitive to those magnetic fields used intentionally to select and manipulate them.
So
boffins were in a bit of a bind. If they they make the qbits in sensitive
they are next to near useless but if they make them insensitive they can't
do much either. How they did it was using two pairs of energy states within
the same atom. One pair is used as a "memory" qubit for storing information,
while the second "working" pair comprises a qubit to be used for computation. When a memory qubit needs to perform a computation, a
magnetic field can make it change hats. And it can do this without
disturbing nearby memory qubits.
They can do this with polarised light,
and the cat neither lives or dies but opens a small Chinese takeaway in
Surrey.