The quantum erasure experiment is a thought experiment that has been realized in various experimental setups, including those involving interference and the use of qubits to store path information.
In a typical quantum erasure experiment, an entangled photon pair is generated, with one photon sent through a double-slit apparatus and the other photon sent to a detector that measures its polarization. The double-slit setup creates an interference pattern, indicating that the photon behaves as a wave and passes through both slits simultaneously. The polarization measurement of the second photon determines which path information is associated with the first photon.
In some variations of the experiment, the which path information of the first photon is "erased" by performing a measurement on the second photon that destroys the path information. This can be achieved by entangling the second photon with an additional quantum system, such as an ancillary qubit, that stores the path information.
By performing specific measurements on the second photon and the ancillary qubit, it is possible to retrieve or erase the which path information of the first photon and observe the corresponding interference pattern or the absence thereof.
The use of qubits to store path information instead of classical bits allows for the manipulation and exploitation of quantum properties, such as superposition and entanglement. Quantum systems can store and process information in ways that classical systems cannot, offering unique advantages in quantum information processing and quantum computing.
Experimental realizations of the quantum erasure experiment have been performed using various physical systems, including photons, atoms, and solid-state devices. These experiments have provided insights into the fundamental aspects of quantum mechanics and the role of measurement in determining the behavior of quantum systems.