Future quantum computers might not be all that different from the one you’re using now. An international team of researchers have created a the most fundamental part of a quantum computer—the quantum bit, or qubit—using only a CMOS transistor that is not much different from those in today’s microprocessors.
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Tomi Engdahl says:
Fredkin Gate Breakthrough Brings Quantum Computing Within Closer Reach
https://news.slashdot.org/story/16/03/28/217220/fredkin-gate-breakthrough-brings-quantum-computing-within-closer-reach
Quantum computers are based on atomic-scale quantum bits, or qubits, that can represent both 0 and 1 simultaneously. Realizing that potential, however, depends on the ability to build working quantum circuits. The quantum version of the classic Fredkin gate exchanges two qubits depending on the value of the third. It could be a key component of quantum circuitry, but because of the complexity involved, no one has ever managed to build one in the real world — until now.
A quantum Fredkin gate
http://advances.sciencemag.org/content/2/3/e1501531
Tomi Engdahl says:
Toward practical quantum computers
Built-in optics could enable chips that use trapped ions as quantum bits
http://news.mit.edu/2016/toward-practical-quantum-computers-0808
Quantum computers are largely hypothetical devices that could perform some calculations much more rapidly than conventional computers can. Instead of the bits of classical computation, which can represent 0 or 1, quantum computers consist of quantum bits, or qubits, which can, in some sense, represent 0 and 1 simultaneously.
Although quantum systems with as many as 12 qubits have been demonstrated in the lab, building quantum computers complex enough to perform useful computations will require miniaturizing qubit technology, much the way the miniaturization of transistors enabled modern computers.
Trapped ions are probably the most widely studied qubit technology, but they’ve historically required a large and complex hardware apparatus. In today’s Nature Nanotechnology, researchers from MIT and MIT Lincoln Laboratory report an important step toward practical quantum computers, with a paper describing a prototype chip that can trap ions in an electric field and, with built-in optics, direct laser light toward each of them.
A standard ion trap looks like a tiny cage, whose bars are electrodes that produce an electric field. Ions line up in the center of the cage, parallel to the bars. A surface trap, by contrast, is a chip with electrodes embedded in its surface. The ions hover 50 micrometers above the electrodes.
“We believe that surface traps are a key technology to enable these systems to scale to the very large number of ions that will be required for large-scale quantum computing,” says Jeremy Sage, who together with John Chiaverini leads Lincoln Laboratory’s trapped-ion quantum-information-processing project. “These cage traps work very well, but they really only work for maybe 10 to 20 ions, and they basically max out around there.”
Performing a quantum computation, however, requires precisely controlling the energy state of every qubit independently, and trapped-ion qubits are controlled with laser beams. In a surface trap, the ions are only about 5 micrometers apart. Hitting a single ion with an external laser, without affecting its neighbors, is incredibly difficult; only a few groups had previously attempted it, and their techniques weren’t practical for large-scale systems.
Tomi Engdahl says:
Practical quantum computers; general-purpose quantum computers;
http://semiengineering.com/system-bits-aug-9/
Using trapped ions as quantum bits
MIT researchers reminded that quantum computers are largely hypothetical devices that could perform some calculations much more rapidly than conventional computers can, and instead of the bits of classical computation — which can represent 0 or 1 — quantum computers consist of quantum bits, or qubits, which can, in some sense, represent 0 and 1 simultaneously.
Tomi Engdahl says:
Ion Trap Makes Programmable Quantum Computer
http://hackaday.com/2016/08/14/ion-trap-makes-programmable-quantum-computer/
The Joint Quantum Institute published a recent paper detailing a quantum computer constructed with five qubits formed from trapped ions. The novel architecture allows the computer to accept programs for multiple algorithms.
Quantum computers make use of qubits and trapped ions–ions confined with an electromagnetic field–are one way to create them. In particular, a linear radio frequency trap and laser cooling traps five ytterbium ions with a separation of about 5 microns. To entangle the qubits, the device uses 50 to 100 laser pulses on individual or pairs of ions. The pulse shape determines the actual function performed, which is how the device is programmable. The operations depend on the sequence of laser pulses that activate it.
Ion-trap quantum computer is programmable and reconfigurable
http://physicsworld.com/cws/article/news/2016/aug/03/ion-trap-quantum-computer-is-programmable-and-reconfigurable
Five-ion trap
Chris Monroe’s group at the Joint Quantum Institute and the Joint Center for Quantum Information and Computer Science, at the University of Maryland in the US, uses trapped ions as qubits. In this technique, information is stored in the atomic-ions’ states. Electromagnetically confining a number of such ions, or “trapping” them, the particles can then be entangled by applying appropriate laser beams. The finely tuned laser light manipulates each ion in a specific way, depending upon its state. “In this way, the collective motion of the chain of ions behaves as a data bus that allows qubits to talk to each other,” say Monroe.
While small ion-trap quantum computers have previously been built, each was a single-purpose device, capable of running a particular algorithm or generating a fixed entangled state. Now though, Monroe, together with Shantanu Debnath and colleagues, has demonstrated that the device can be programmed with multiple algorithms.
Tomi Engdahl says:
System Bits: Nov. 29
300mm quantum demo
http://semiengineering.com/system-bits-nov-29/
Qubit device fabbed in standard CMOS
In a major step toward commercialization of quantum computing, Leti, an institute of CEA Tech, along with Inac, a fundamental research division of CEA, and the University of Grenoble Alpes have achieved the first demonstration of a quantum-dot-based spin qubit using a device fabricated on a 300-mm CMOS fab line.
Maud Vinet, Leti’s advanced CMOS manager said, “This proof-of-concept result, obtained using a CMOS fab line, is driving a lot of interest from our semiconductor industrial partners, as it represents an opportunity to extend the impact of Si CMOS technology and infrastructure beyond the end of Moore’s Law.”
The proof-of-concept breakthrough uses a device fabricated on a 300-mm CMOS fab line consisting of a two-gate, p-type transistor with an undoped channel. At low temperature, the first gate defines a quantum dot encoding a hole spin qubit, and the second one defines a quantum dot used for the qubit readout. All electrical, two-axis control of the spin qubit is achieved by applying a phase-tunable microwave modulation to the first gate, the team explained.
The one-qubit demonstrator brings CMOS technology closer to the emerging field of quantum spintronics.
Vinet added: “This proof-of-concept result, obtained using a CMOS fab line, is driving a lot of interest from our semiconductor industrial partners, as it represents an opportunity to extend the impact of Si CMOS technology and infrastructure beyond the end of Moore’s Law. The way toward the quantum computer is still long, but CEA is leveraging its background in physics and computing, from technology to system and architecture, to build a roadmap toward the quantum calculator.”
A CMOS silicon spin qubit
http://www.nature.com/articles/ncomms13575
Tomi Engdahl says:
System Bits: May 30
Diamonds for quantum computing
https://semiengineering.com/system-bits-may-30/
Quantum computers are experimental devices that offer large speedups on some computational problems, and one promising approach to building them involves harnessing nanometer-scale atomic defects in diamond materials. At the same time, practical, diamond-based quantum computing devices will require the ability to position those defects at precise locations in complex diamond structures, where the defects can function as qubits, the basic units of information in quantum computing. Now, a team of researchers from MIT, Harvard University, and Sandia National Laboratories has reported a new technique for creating targeted defects, which is simpler and more precise than its predecessors.
Toward mass-producible quantum computers
Process for positioning quantum bits in diamond optical circuits could work at large scales.
http://news.mit.edu/2017/toward-mass-producible-quantum-computers-0526
Tomi Engdahl says:
New silicon structure opens the gate to quantum computers
December 12, 2017
https://m.phys.org/news/2017-12-silicon-gate-quantum.html
In a major step toward making a quantum computer using everyday materials, a team led by researchers at Princeton University has constructed a key piece of silicon hardware capable of controlling quantum behavior between two electrons with extremely high precision. The study was published Dec. 7 in the journal Science.
Tomi Engdahl says:
Silicon CMOS Architecture For A Spin-based Quantum Computer
https://semiengineering.com/silicon-cmos-architecture-for-a-spin-based-quantum-computer/
UNSW researchers have shown how a quantum computer can be manufactured using mostly standard silicon technology.