The spin state of a single electron in a quantum dot has been measured for the first time without destroying the state. David Awschalom and colleagues at University of California, Santa Barbara, determined the spin by reflecting polarized laser light from a quantum dot. The development could lead to the exploitation of the quantum properties of single electrons in quantum computers.
Quantum computers could exploit the fact that a quantum particle can be in two states at the same time spin up or spin down in the case of an electron. With the two states representing a one or a zero, N such particles or quantum bits (qubits) could be combined or entangled to represent 2N values simultaneously. This could lead to the parallel processing of information on a massive scale. However, the realization of a quantum computer involves fundamental challenges such as how to read the logical state of a qubit without destroying the state, and how to entangle the qubits.
Semiconductor quantum dots are nanoscale structures that contain as few as one electron and show great promise for use as qubits. Information can be stored in the spin state of a single electron and while several optical and electronic schemes exist for reading the spin state, they all destroy the state as part of the process.
Leído en physicsweb.com.