Sending Quantum Information Securely from Laser Light to a Quantum Dot

Scientists from Osaka University have demonstrated how information encoded in the circular polarization of a laser beam can be translated into the spin state of an electron in a quantum dot (QD). They used laser light to send quantum information to a QD by altering the spin state of a single electron trapped on the QD. “This action allowed us to read the state of the electron after applying the laser light to confirm that it was in the correct spin state,” professor Takafumi Fujita said. Although electrons don’t spin in the traditional sense, they do have angular momentum, which can be flipped when absorbing circularly polarized laser light. The researchers used a Pauli spin blockade in a double QD to verify...