Quantum behavior of millimeter-sized magnets unraveled
Researchers in the University of Tokyo have demonstrated that it is possible to exchange a quantum bit, the minimum unit of information used by quantum computers, between a superconducting quantum-bit circuit and a quantum in a magnet called a magnon. This result is expected to contribute to the development of quantum interfaces and quantum repeaters.
Magnets, often used in our daily life, exert a magnetic force produced by a large number of microscopic magnets – the spins of individual electrons – that are aligned in the same orientation. The collective motions of the ensemble of spins are called spin waves.
A magnon is a quantum of such excitations, similar to a photon as a quantum of light, i.e., the electromagnetic wave. At room temperature the motions of electron spins can be largely affected by heat. The properties of individual magnons have not been studied at low temperatures corresponding to the “quantum limit” where all thermally-induced spin fluctuations vanish.
The research group of Professor Yasunobu Nakamura at the University of Tokyo Research Center for Advanced Science and Technology has succeeded for the first time to couple a magnon in a magnet to a photon in a microwave cavity at an ultralow temperature near absolute zero (-273.14 degrees centigrade). They observed coherent interaction between a magnon and a microwave photon by placing a millimeter-sized ferromagnetic sphere made of yttrium iron garnet in a centimeter-scale microwave cavity.
The research group furthermore demonstrated coherent coupling of a magnon to a superconducting quantum-bit circuit. The latter is known as a well-controllable quantum system and as one of the most promising building blocks for quantum processors. The group placed the magnet together with the superconducting qubit in a cavity and demonstrated exchange of information between the magnon and superconducting qubit mediated by the microwave cavity.
The results will stimulate research on the quantum behavior of magnons in spintronics devices and open a path toward realization of quantum interfaces and quantum repeaters.
*A magnet (ytterium iron garnet; YIG) and a superconducting qubit are placed with a separation of 4 cm. The electric field in the cavity interacts with the qubit, while the magnetic field interacts with the magnet. At an extremely low temperature of around -273 degrees centigrade, magnons, i.e., quanta of the fluctuations in the magnet, coherently couple with the qubit through the electromagnetic field of the cavity.
UTokyo Research article
Euan McKay | ResearchSea
New type of smart windows use liquid to switch from clear to reflective
14.12.2017 | The Optical Society
New ultra-thin diamond membrane is a radiobiologist's best friend
14.12.2017 | American Institute of Physics
MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.
Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...
Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...
Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.
To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...
The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.
Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...
With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong
Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...
11.12.2017 | Event News
08.12.2017 | Event News
07.12.2017 | Event News
14.12.2017 | Health and Medicine
14.12.2017 | Physics and Astronomy
14.12.2017 | Life Sciences