Reading the value of a qubit without changing its value

[dmtr]

From the http://physicsworld.com/cws/article/news/23637

The effect could be used to read out quantum bits (qubits) in a reliable way because the quantum capacitance of the excited state of the qubit has the opposite sign to the ground state. These states could be used as the "1s" and "0s" in a quantum computer. Indeed Hakonen and colleagues have already used this approach to read the value of a qubit without changing its value -- which is almost always a problem when measuring the quantum state of any system.

How can that be possible? Isn't that a violation of the No-cloning theorem?

 

[Neo_Anderson]

Their was a phase change in the RF signal that was sent to the Cooper-pair transistor. This phase change corresponds to the ground state and the excited state of the electron that tunneled through the dielectric.
Because the phase change was observed without actually disturbing the transistor, their knowledge of the state of the tunneled electron is now known, and the no-cloning theorem demands that the state of the tunneled electron be always unknown and arbitrary.