Qubits tagged posts

Electrodes stretch diamond strings to increase the frequency of atomic vibrations to which an electron is sensitive, just like tightening a guitar string increases the frequency or pitch of the string. The tension quiets a qubit’s environment and improves memory from tens to several hundred nanoseconds, enough time to do many operations on a quantum chip. (Second Bay Studios/Harvard SEAS)

A process similar to guitar tuning improves storage time of quantum memory. A quantum internet promises completely secure communication. But using quantum bits or qubits to carry information requires a radically new piece of hardware – a quantum memory. This atomic-scale device needs to store quantum information and convert it into light to transmit across the network.

A major challenge to this vision i...

Schematic illustration of a hybrid information network with two quantum nodes composed by a cold cloud of Rubidium (left red cloud) and a doped crystal with Praseodymium ions (right white cube). Credit: ICFO/Scixel

Researchers report the first demonstration of an elementary link of a hybrid quantum information network, using a cold atomic cloud and a doped crystal as quantum nodes as well as single telecom photons as information carriers. The study demonstrates the communication and transmission of quantum information between 2 completely different types of quantum nodes placed in different labs.

Recent research suggests that this quantum network revolution might be just around the corner...

An artist’s rendering of the quantum Fredkin (controlled-SWAP) gate, powered by entanglement, operating on photonic qubits. Credit: Raj Patel and Geoff Pryde, Center for Quantum Dynamics, Griffith University.

The quantum circuit Fredkin gate has been experimentally realised for the first time. “Similar to building a huge wall out lots of small bricks, large quantum circuits require very many logic gates to function. However, if larger bricks are used the same wall could be built with far fewer bricks,” said Dr Patel. “We demonstrate in our experiment how one can build larger quantum circuits in a more direct way without using small logic gates.”

At present, even small and medium scale quantum computer circuits cannot be produced because of the requirement to integrate so many of these gate...

A new strategy helps quantum bits stay on task. Credit: Image courtesy of Florida State University

Development of quantum computers may be expedited by collaboration between physicists and chemists. Quantum computer power will dwarf that of today’s machines, with huge implications for cryptography, computational chemistry and other fields. While qubits can take many different forms, the MagLab team worked with carefully designed tungsten oxide molecules that contained a single magnetic holmium ion. The magnetic electrons associated with each holmium ion circulate either clockwise or counterclockwise around the axis of the molecule. These spin states are analogous to the “0s” and “1s” of computer bits...