The world’s fastest quantum 2-bit logic gate

During the last two decades, attempts have been made to find faster logic gates for all quantum computing hardware that allow avoiding the effects of external “noise” capable of degrading the precision of the calculations executed by the system.

Now scientists have created and tested the world’s fastest quantum 2-bit logic gate, using an innovative manipulation method based on an ultrafast laser and super-cooled atoms.

The achievement is the work of the team of Yeelai Chew, Sylvain de Léséleuc and Kenji Ohmori, from the Institute of Molecular Science in Japan

Chew and his colleagues used atoms cooled to near absolute zero and trapped in optical tweezers. Absolute zero, minus 273.15 degrees Celsius, is the lowest temperature allowed by the laws of physics. Optical tweezers are a system based on laser beams with which it is possible to attract atoms and imprison them.

By manipulating the atoms with this laser system, emitting flashes of only 10 picoseconds (trillionths of a second), they managed to activate the fastest two-qubit gate in the world, which performs each operation in 6.5 nanoseconds (billionths of a second).

Conceptual schematic of the world’s fastest two-qubit gate. Two atoms captured with optical tweezers (red light) are manipulated by an ultrafast laser pulse (blue light) that emits flashes lasting just 10 picoseconds. (Image: Takafumi Tomita (IMS))

Having logic gates like this one, it will be possible to build quantum computers with a different architecture capable of outperforming the most common models being worked on, which are those based on superconductors and those based on trapped ions.

Since atoms are natural quantum systems, they can easily store quantum bits of information. The coherence time (the time during which the quantum superposition persists) of a qubit can reach several seconds.

Chew and his colleagues expose the technical details of their achievement in the academic journal Nature Photonics, under the title “Ultrafast energy exchange between two single Rydberg atoms on the nanosecond timescale.” (Font: NCYT by Amazings)