##

Projective measurement with projectors

Note: Measurement has not yet been implemented for a mixed state.
It works only for a pure state kept as a vector.
An available type of observable for a measurement in this software is
currently only the type:
with
where
is a
number written by using binary numbers (
) and
are computational basis vectors of qubits whose
labels are specified by a user.

- To specify the binary values to be measured (measurement result)
(0 or 1) for measured qubits, use the command:
M (bit labels,
);

* The ``bit labels'' is a string in the style of ``1-6'' (qubit 1
to qubit 6) and/or ``1 3 5'' (qubit 1, 3, and 5).
is the string of the binary values to be measured for
the qubits of ``bit labels''.
You may type like this:
M (1-8, 1 0 0 1 0 1 1 1);

The qubits that are not measured will properly transit to the state after the
measurement.

Example for the read-line mode:
> init 0 0;
> H(1); CN(1,2);
> showb;
0.707107|00> + 0.707107|11>
> M(1,0);
> showb;
1|00>

- When you do not specify the result of measurement,
the measured qubits result in 0 or 1 with the corresponding
probabilities. Such a transition is controlled by a random seed that is
produced from the current local time of a computer.
For an example, you may try the above example
with the line
M(1);

instead of `M(1,0);`

.

*root *

2004-11-07