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Archive for the ‘quantum physics’ category: Page 7

May 31, 2019

Quantum error correction and universal gate set operation on a binomial bosonic logical qubit

Posted by in category: quantum physics

Repeated error correction creates a logical qubit encoded in the hybrid state of a superconducting circuit and a bosonic cavity, which is shown to be fully controllable under a universal single-qubit gate set.

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May 31, 2019

Physicists measure how long graphene qubits hover in “alive/dead” superposition

Posted by in categories: computing, quantum physics

Practical quantum computers may be another step closer to reality – and like so many technologies, we have graphene to thank for it. The bits of information in quantum computers (qubits) can famously exist in two states at once, and now researchers from MIT and other institutions have managed to record just how long that superposition state can last in a qubit made of graphene.

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May 31, 2019

The defect-free assembly of 2-D clusters with over 100 single-atom quantum systems

Posted by in categories: particle physics, quantum physics

Researchers at Technische Universität Darmstadt have recently demonstrated the defect-free assembly of versatile target patterns of up to 111 single-atom quantum systems. Their findings, outlined in a paper published in Physical Review Letters, could drive assembled-atom architectures beyond the threshold of quantum advantage, paving the way for new breakthroughs in quantum science and technology.

“Our research is driven by the observation that physical sciences are right in the middle of a paradigm shift in which the application of physics, i.e. quantum technologies, are becoming the leading technologies in the near future,” Gerhard Birkl, one of the researchers who carried out the study, told Phys.org. “A vast list of applications are already foreseeable but I am convinced that of most applications we are not even aware of.”

The next step for the field of and technology is the development of experimental platforms that offer extensive scalability, multisite quantum correlations and efficient quantum error correction. Over the past century or so, researchers have carried out a substantial amount of work on single quantum systems, laying the foundations for current developments. Atomic quantum systems have played a key role in these studies, particularly neutral atoms trapped by light, as they provide well-isolated quantum systems with favorable scaling.

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May 31, 2019

How a quantum computer could break 2048-bit RSA encryption in 8 hours

Posted by in categories: computing, encryption, quantum physics

A new study shows that quantum technology will catch up with today’s encryption standards much sooner than expected. That should worry anybody who needs to store data securely for 25 years or so.

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May 30, 2019

Study points to non-Newtonian force affecting particles’ flight

Posted by in categories: particle physics, quantum physics

The quotation marks had the force of tradition—and the tradition of force—behind them.

When Nebraska’s Herman Batelaan and colleagues recently submitted a research paper that makes the case for the existence of a non-Newtonian, quantum force, the journal asked that they place “force” firmly within quotes. The team understood and agreed to the request.

After all, the word has long belonged to classical Newtonian physics: equal-and-opposite reactions, electromagnetism, gravity and other laws that explain the apple-dropping, head-bonking phenomena of everyday experience.

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May 29, 2019

On-demand, photonic entanglement synthesizer

Posted by in categories: engineering, quantum physics

Quantum information protocols are based on a variety of entanglement modes such as Einstein-Podolsky-Rosen (EPR), Greenberger-Horne-Zeilinger (GHZ) and other cluster states. For on-demand preparation, these states can be realized with squeezed light sources in optics, but such experiments lack versatility as they require a variety of optical circuits to individually realize diverse states of entanglement. In a recent study, Shuntaro Takeda and colleagues at the interdisciplinary departments of Applied Physics and Engineering in Japan addressed the shortcoming by developing an on-demand entanglement synthesizer. Using the experimental setup, the physicists programmably generated entangled states from a single squeezed source of light.

In the work, they used a loop-based circuit dynamically controlled at nanosecond time scales to process optical pulses in the time domain. The scientists generated and verified five different small-scale entangled states and a large-cluster containing more than 1000 modes in a single setup without changing the optical circuit. The circuit developed by Takeda et al. could store and release one part of the generated entangled states to function as a quantum memory. The experimental report published on Science Advances, will open a new way to build general entanglement synthesizers on-demand using a scalable quantum processor.

Entanglement is essential for many quantum information protocols in qubit and continuous variable (CV) regions, where they perform a variety of applications. For instance, the two-mode Einstein-Podolsky-Rosen (EPR) state is the most commonly used, maximally entangled state as a building block for two-party quantum communication and for quantum logic gates based on quantum teleportation. The generalized version of this state is an n-mode Greenberger-Horne-Zeilinger (GHZ) state central to building a quantum network, where the GHZ quantum state can be shared between n participants. For example, the n participants can communicate with each other for quantum secret sharing. For quantum computation on the other hand, a special type of entanglement known as cluster states has attracted much attention as a universal resource to allow one-way quantum computation.

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May 29, 2019

Soon ‘noise-cancelling headphones’ for quantum computers

Posted by in categories: computing, quantum physics

Quantum computers encode information in delicate superposition states of quantum bits, or ‘qubits’.

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May 29, 2019

Quantum noise and stochastic reduction

Posted by in categories: evolution, information science, law, quantum physics

Abstract: In standard nonrelativistic quantum mechanics the expectation of the energy is a conserved quantity. It is possible to extend the dynamical law associated with the evolution of a quantum state consistently to include a nonlinear stochastic component, while respecting the conservation law. According to the dynamics thus obtained, referred to as the energy-based stochastic Schrodinger equation, an arbitrary initial state collapses spontaneously to one of the energy eigenstates, thus describing the phenomenon of quantum state reduction. In this article, two such models are investigated: one that achieves state reduction in infinite time, and the other in finite time. The properties of the associated energy expectation process and the energy variance process are worked out in detail. By use of a novel application of a nonlinear filtering method, closed-form solutions—algebraic in character and involving no integration—are obtained for both these models. In each case, the solution is expressed in terms of a random variable representing the terminal energy of the system, and an independent noise process. With these solutions at hand it is possible to simulate explicitly the dynamics of the quantum states of complicated physical systems.

From: Dorje C. Brody [view email]

[v1] Mon, 29 Aug 2005 13:22:36 UTC (43 KB)

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May 29, 2019

Quantum Invisibility Cloak Hides Objects from Reality

Posted by in category: quantum physics

Physicists have worked out how to cloak a region of space from the quantum world, thereby shielding it from reality itself.

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May 28, 2019

Honeywell One Step Closer To Universal Quantum Computer

Posted by in categories: computing, quantum physics

The quantum computing effort at Honeywell appears to be heating up. Over the last several months, the company has announced a series of new developments in its trapped ion quantum computer research, which suggests that it is close to launching its first system.

If you weren’t aware that Honeywell had a quantum computing program, you are not alone. While the occasional terse news statement about this effort is posted on the company’s quantum solutions page, the tech giant has otherwise been rather tight-lipped about its plans in this area. A request from us for more information was met with: “We don’t have anything further to add on this front.”

Since October of last year, Honeywell has been offering these smaller tidbits on a regular basis. In November, the company revealed it had started testing its first-generation qubit devices, followed in January by the claim that it had “demonstrated record-breaking high fidelity quantum operations” on its trapped-ion qubits. In March, it announced it had demonstrated “parallel operating zones” on the device, which it believes will provide faster execution and more flexible qubit connectivity.

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