When a quantum computer is measured, the state of its quantum bits, or qubits, collapses to one of the possible measurement outcomes. The act of measurement in quantum mechanics causes a wavefunction collapse, where the superposition of multiple states reduces to a single state.
In quantum computing, qubits are fundamental units of information that can exist in a superposition of states, representing both 0 and 1 simultaneously. This property enables quantum computers to perform certain computations more efficiently than classical computers for specific problems.
However, when a measurement is made on a qubit, the superposition collapses, and the qubit assumes a definite value. The result of the measurement is one of the possible classical states corresponding to the probability amplitudes of the qubit. For example, if a qubit is in an equal superposition of 0 and 1, a measurement will yield either 0 or 1 with certain probabilities based on the amplitudes.
The measurement process disturbs the delicate quantum state, and subsequent measurements will generally not produce the same result. This collapse of the quantum state is a fundamental aspect of quantum mechanics and distinguishes it from classical probabilistic systems.
To summarize, when a quantum computer is measured, the superposition of the qubits collapses to a definite state, and the measurement result corresponds to one of the possible outcomes with certain probabilities.