Ultrafast Gates in Atomic Qubits
PFC experimentalists in the Trapped Ion Quantum Information group have performed a gate that flips the state of a single atomic qubit in less than 50 picoseconds. The time to perform this same operation with continuous wave (CW) lasers, a standard for these types of atomic systems, is typically over 10,000 times slower.
In conventional computers a bit can be in the state 0 or 1, but not both simultaneously. By contrast, a quantum bit, or qubit, can reside in a combination of the two states.Qubits can made from any quantum system having two energy levels. In this experiment, the qubit is a laser cooled, singly ionized Ytterbium atom having two ground state electronic levels labeled  and , or up and down. The state of this system can be controllably manipulated with lasers or microwave radiation.
The researchers drive qubit rotations using a highly energetic single pulse or by optically dividing the pulse into two counterpropagating pulses. The gate, whether performed with CW or pulsed lasers, is a process that requires two photons. Here, the key technology is an ultraviolet laser that emits a pulse of light that is 10 picosecond longevery 8 nanoseconds. Within each individual pulse there are photons that have the frequency separation required (12.6 GHz) to coherently manipulate the qubit.
Subscribe to A Quantum Bit
Quantum physics began with revolutionary discoveries in the early twentieth century and continues to be central in today’s physics research. Learn about quantum physics, bit by bit. From definitions to the latest research, this is your portal. Subscribe to receive regular emails from the quantum world. Previous Issues...
Sign Up Now
Sign up to receive A Quantum Bit in your email!