Quantum teleportation over 143km smashes distance record
2012.09.07.11:10
International researchers say their work paves the way for global quantum communications. Next up: the quantum internet?
IBM creates 1Tbps Holey Optochip
2012.03.08.06:42
Researchers at IBM have created an optical computer chip that can transmit and receive data at up to one terabit per second (1Tbps).
http://www.extremetech.com/computing/121587-ibm-creates-cheap-standard-cmos-1tbps-holey-optochip
IBM shows off quantum computing advances, says practical qubit computers are close
All in all, IBM Research is now saying that bona fide quantum computers are now just 10 to 15 years away. Why is this significant? Well, put it this way: According to IBM, 250 qubits would be able to store “more bits of information than there are atoms in the universe.” This in itself is truly awesome — but then when you factor in that a quantum computer could perform logic on all of that data, in parallel, instantaneously… well, you begin to see the power of quantum computing. You’re talking about the performance of a supercomputer on a single chip.
http://www.extremetech.com/extreme/120229-ibm-shows-off-quantum-computing-breakthroughs-says-qubit-computers-are-close
Quantum Qubits
Physicists at UC Santa Barbara have discovered a quality of silicon carbide — a material commonly used in the manufacture of semiconductors — that can be used to perform quantum computing.
http://www.extremetech.com/extreme/103237-quantum-qubits-found-in-cheap-mass-produced-semiconductor?obref=obinsite
Moving Data from Matter to Light
By William Van Winkle, 2005.01.01
You’ve probably grasped the fundamental idea in quantum computing that a qubit (quantum bit), unlike a traditional bit, can simultaneously exist in the states of 0 and 1. These values are typically noted in terms of the qubit having a spin-up or spin-down state. Additionally, qubits can become entangled such that they share the same state, and changing the state of one qubit instantly changes the state of the other.
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Getting qubits to exist in their ambiguous state of “superposition” is hard enough, but communicating qubit data beyond the test chamber is essential for quantum-based networks. In essence, this requires transferring a quantum state from atomic media (matter) to photons (light). A matter-based system is fine for storage, but because many quantum computers are likely to be based on distributed models, a photonic system is essential. With funding from NASA and the Research Corporation, assistant professor Alex Kuzmich and graduate student Dzmitry Matsukevich of Georgia Tech’s School of Physics have demonstrated a way to achieve this.
The duo used two clouds of extremely cold rubidium atoms, each with about 1 billion atoms. Each cloud, or ensemble, possessed a different quantum state, thus forming a nebulous qubit. They split an infrared laser beam, passed each beam through its own ensemble, and after carefully calculated light scattering, polarization, and reflection, recombined the beam. The resulting qubit proved to be entangled with an individual photon.
“Nobody has been able to take a matter qubit and convert it to a light qubit,” says Kuzmich. “This basic building block for future quantum networks is the first step toward realizing a quantum repeater. Having quantum repeaters would allow us to realize quantum communications that would not be limited by the absorption loss of the optical fiber.”
Besides its suitability for long distance transmission, photonic qubits never need to be converted back into matter, as quantum computers can process photons as well as atomic qubits. However, Kuzmich estimates that marketable applications of the process are still nearly a decade away.
Purdue Prof Sorts Quantum Streams
By William Van Winkle, 2005.01.01
Another potentially major leap in quantum computing occurred recently when Purdue University researchers were able to segregate qubits according to their spin orientation. If a collection of qubits are all performing computation in their state of superposition, they collapse into a definite up or down state once the computation is complete, and you’re still left with sorting those qubits, measuring how many of which type you have. Until now, all approaches at performing this segregation have failed.
Leonid P. Rokhinson, assistant physics professor at Purdue, and his team found that highly purified gallium arsenide semiconductors sandwiched between layers of aluminum gallium arsenide possessed just the right ability to split a stream of quantum objects according to their spin. In this case, a beam of “holes” in the gallium arsenide, or the spaces electrons leave as they pass through the semiconductor, was bent with a magnetic field along two different cyclotron trajectories.
“Although it may seem counterintuitive, the holes have a spin state, as well,” says Rokhinson in a statement. “The spaces don’t literally spin; the idea of spin is just a loose metaphor anyway to help physicists imagine what’s going on. In an electric current flowing through a copper wire, we imagine electrons jumping from one copper atom’s orbital hole to another. We could also imagine those holes having a positive charge and flowing in the opposite direction. A similar concept is at work here with spin state; we’re just working with the holes this time, not the particles.”
Rokhinson says spin segregation will be vital to any spin based device functioning and “could be one of the missing links necessary for the development of quantum computers and nonvolatile memory devices.” The Purdue approach doesn’t require the large magnetic fields typical of other spin-measurement efforts. It does require operational temps just above 0 degrees Kelvin. If researchers can raise the operational temps and manipulate the electron holes, they’ll be closer to a practical spin-based transistor.