Kvanttitomografiaassa

Kvanttitomografiaassa, also known as quantum tomography, is a technique used to reconstruct the quantum state of a quantum system. It is analogous to classical tomography, which uses projections to determine the internal structure of an object. In quantum tomography, instead of classical projections, measurements are performed on the quantum system in different bases. By analyzing the results of these measurements, it is possible to reconstruct the density matrix or state vector that describes the quantum state.

The process typically involves preparing a large number of identical copies of the quantum state. Each copy is then subjected to a specific measurement. For a single qubit, measurements in the computational basis (representing states |0⟩ and |1⟩) and the diagonal basis (representing states |+⟩ and |−⟩) are often sufficient. More complex systems require measurements in a larger set of bases. The probabilities of obtaining different outcomes for each measurement are recorded. These probabilities are directly related to the elements of the density matrix.

Once a sufficient number of measurements in a set of linearly independent bases are performed, the density matrix can be computationally reconstructed. This allows for a complete characterization of the quantum state, including information about superposition and entanglement. Quantum tomography is a crucial tool for verifying the performance of quantum devices, such as quantum computers and quantum simulators, and for understanding fundamental quantum phenomena. Its accuracy is limited by experimental noise and the number of measurements performed.