Converting quantum bits
Alex Kuzmich and Dzmitry Matsukevich have transferred atomic state information from two clouds of rubidium atoms to a single photon.
A team of physicists at the Georgia Institute of Technology has taken a significant step toward the development of quantum communications systems by successfully transferring quantum information from two different groups of atoms onto a single photon.
The work, to be published in the October 22 issue of the journal Science, represents a "building block" that could lead to development of large-scale quantum networks. Sponsored by the Research Corporation and NASA, the work is believed to be the first to demonstrate transfer of quantum information from matter to light.
Conversion of quantum states from atomic-based systems to photonic systems is necessary for long-distance communication. While the matter-based systems can provide long-term storage of information, efficient transfer of information requires that it be converted into a photonic state for transmission across optical fiber networks.
Once converted into a photonic qubit, the information can be processed and may not need to be converted back to a matter-based qubit. "If you want to realize a quantum repeater, you must have two such quantum nodes," Kuzmich explained. "But in this quantum communications approach, you dont ever need to convert the photon back to atomic format."
For their research, the Georgia Tech physicists used light at a wavelength of 780 nanometers. For transmission in conventional optical fiber networks, however, they will have to switch to the 1550 nanometer wavelength that has become standard in the telecommunications industry. The Science paper reported on atom clouds containing approximately a billion rubidium atoms. Kuzmich says having 10 billion atoms compressed into the same space would boost efficiency. "We should be able to increase our efficiency by a factor of ten at least," he said. Practical applications are still at least 7-10 years away, Kuzmich estimates.
Detailed Explanation of Experiment Diagram: A magneto-optical trap is used to provide an optically thick atomic cloud of a billion rubidium atoms for the experiment. The classical coherent laser pulses used in the generation and verification procedures define the two distinct pencil-shape components of the atomic ensemble that form the memory qubit, L and R.
An infrared write pulse (780 nm wavelength) is split into two beams by a polarizing beam splitter (PBS1) focused into two regions of the atomic cloud about 1 mm apart and passed through it. The light induces spontaneous Raman scattering of a signal photon with slightly shorter wavelength. The classical light is dumped away by the PBS2, while the quantum signal photon is transmitted by the dichroic mirror DM, passed through an arbitrary polarization state transformer R and a polarizer PBS5, and is directed onto a single-photon detector D1. Detection of the signal photon by D1 prepares the atomic ensemble in any desired state and thereby concludes the preparation of the quantum memory qubit.
Following memory state preparation, the read-out stage is performed. After a user-programmable delay a classical coherent read pulse of 795 nm wavelength illuminates the two atomic ensembles. This results in a single (i.e., quantum) idler photon being emitted in the forward direction. This accomplishes a transfer of the memory state onto the idler. The idler is reflected off the dichroic mirror DM. After passing through the state transformer R and PBS6, the two polarization components are directed onto single-photon detectors (D2, D3) thus accomplishing measurement of the idler photon, and hence the memory qubit, in a controllable arbitrary basis.
John Toon | EurekAlert!
Move over, lasers: Scientists can now create holograms from neutrons, too
21.10.2016 | National Institute of Standards and Technology (NIST)
Finding the lightest superdeformed triaxial atomic nucleus
20.10.2016 | The Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...
COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.
In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...
'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.
Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
21.10.2016 | Health and Medicine
21.10.2016 | Information Technology
21.10.2016 | Materials Sciences