#hyperEntanglement

[govindhtech]

Hyper Entanglement: Atomic Vibrations Enable Superposition

Quantum Control: Caltech Physicists Improve Computing and Hyper Entanglement with Atomic Motion Caltech researchers under Professor Manuel Endres have improved quantum system control by using unwanted atomic motion to encode quantum information. An important experiment showed hyper-entanglement in large particles like neutral atoms.

It describes a new quantum information storage and manipulation technology that could improve simulation, quantum computing, and precision measurement. Professor Endres controls atoms with laser-powered optical tweezers. His team uses these tweezers to move atoms in arrays to study quantum systems. The regular jiggling motion of atoms has made these systems harder to govern, but the Caltech scientists cleverly reversed this. Disorder to Asset Co-lead author Adam Shaw (PhD ’24) says, “It demonstrates that atomic motion, which is generally regarded as a form of undesired noise in quantum systems, can be transformed into a strength.” Researchers encoded quantum information using this motion to solve a long-standing challenge. This approach required cooling optical tweezers' alkaline-earth neutral atom arrays. The team compares ‘erasure cooling’ to James Clerk Maxwell’s 1867 thought experiment in which a demon sorts and measures particles. Maxwell's demon Endres says it measures atom motion and performs an operation. This technology drove atoms to near-total stillness, outperforming the best laser cooling methods.

Hyper Entanglement Unlocked

After cooling, the scientists caused atoms to oscillate 100 nanometres. They excited the atoms into two oscillations to generate superposition. Superposition allows a particle to have opposite properties like an up-and-down spin. Endres compared an atom in superposition to a child on a swing pushed by two parents on opposite sides. They linked atoms' movements over several micrometres from this condition. This was revolutionary: they hyper-entangled these combinations. Due to normal entanglement, measuring one particle's characteristic immediately yields the other's characteristic, regardless of distance. For instance, if one particle's spin is up, the second may always be down. Further, hyper entanglement links two particle attributes. This is like twins who were born separated but had the same names and car models. At Caltech, the team highly entangled pairs of atoms to connect their internal energy levels, states of motion, and electrical states. We can encode more quantum information per atom. Resource scarcity increases entanglement. This experiment shows super entanglement in neutral atoms or ions for the first time. Photons showed it before. Building the Quantum Toolbox It boosts quantum control. Pushing atomic control limitations was the goal.Kind of like building a toolbox: It originally regulated an atom's electron motion and now controls its outer motion. Like a fully mastered toy atom. Conclusion Caltech physicists created hyper entanglement in atoms using novel cooling and control technologies. By carefully manipulating atom mobility with optical tweezers, they established entangled positions and intrinsic characteristics. This Science article highlights the potential of using atoms as building blocks for future quantum systems, which could improve quantum computing and related technologies. The surrounding content, including a list of related topics and other articles, suggests that the text is an article or excerpt from a quantum and emerging technology journal.

[sisiad]

Optical scheme for generating hyperentanglement having photonic qubit and time-bin via quantum dot and cross-Kerr nonlinearity

http://dlvr.it/QFMcSH

[qutronics]

via QuNews

[mthrynn]

Using a technique called superdense coding, researchers from Oak Ridge National Laboratory have set a new record for data density transmission – 1.67 bits per qubit, or quantum bit – over a fiber optic cable. Noteworthy, they used relatively non-exotic components suggesting the technique may be moving closer, albeit slowly, towards practical use.

Brian Williams, ORNL

A report on the work (Superdense coding over optical fiber links with complete Bell-state measurements) by ORNL researchers Brian Williams, Ronald Sadlier and Travis Humble was published yesterday in Physical Review Letters. The research was selected as an “Editor’s Suggestion,” a distinction reserved for approximately one in six PRL papers.

Quantum behavior offers many tantalizing prospects for computing and communications. Whereas classical computers transmit information in the form of bits (usually a 1 or 0), qubits can employ two states simultaneously (superposition) and represent more information than a traditional bit. The physics of this quantum communication task employed by Williams and his team is similar to that used by quantum computers, which use qubits to arrive at solutions to extremely complex problems faster than their bit-laden counterparts.

(Left) The original four-color 100 × 136 pixel 3.4 kB image. (Right) The image received using superdense coding. The calculated fidelity was 87%.

A brief article on the work is posted on the ORNL web site and a synopsis is on the APS Physics website. As a demonstration of the technique’s effectiveness, the team transmitted the ORNL logo, an oak leaf, between two end points in the laboratory.

A significant part of the challenge in superdense coding such as that used by the ORNL team is the need to perform a complete Bell-state measurement (BSM) on the photon pair; it’s not possible using only linear optics and a single degree of shared entanglement. Non-linear optics can be used for successful BSM but have proven inefficient and complicated to implement.

In the paper, the researcher write, “Our novel interferometric design allows ‘off-the-shelf’ single-photon detectors to enable the complete Bell-state discrimination instead of the number-resolving detectors required by previous experiments. To our knowledge, this is the first demonstration of superdense coding over an optical fiber and a step towards the practical realization of superdense coding. Alongside our demonstration of a hybrid quantum-classical transfer protocol, these results represent a step toward the future integration of quantum communication with fiber-based networks.” See figure from the paper below.

Quantum communication and computing are indeed fascinating but also puzzling for most of us. It’s best to read the original paper. That said, here’s an excerpt from the APS synopsis (by Michael Schirber) describing the ORNL work:

“Suppose Alice wants to send a two-bit message to Bob. She could send two photons with the message encoded in their polarizations. Or, using superdense coding, she could send one polarized photon qubit whose polarization state encodes both bits. The latter option requires that the two parties initially share a pair of photons with entangled polarization. Alice performs one of four operations on her photon and then sends it to Bob, who combines it with his photon to measure which operation Alice performed.

“If Bob simply measures polarization, then he won’t recover the full message. One solution is to entangle the photons in some additional degree of freedom, such as orbital angular momentum. But so far, these hyperentangled states have been unable to survive transmission through optical fibers. Williams and his colleagues have devised a superdense coding system that is fiber compliant. In this case, Alice and Bob’s photons pass through an interferometer whose arms incorporate time delays that entangle the arrival times of the photons at the detectors. Using polarization and arrival-time measurements, Bob can recover Alice’s message at a density of 1.67 bits per qubit. This is not yet the maximum density of 2, but it sets a new record for a system using single photons and linear optics.”

There are still many challenges. For example, the ORNL logo (see figure) was only transmitted with ~87 percent fidelity. “[E]rrors in the received image result from drift in the interferometer during transmission, phase miscalibration, and imperfect state generation.”

Link to paper: http://ift.tt/2jx9SUq

Link to ORNL article: http://ift.tt/2jVY7mU

Link to APS Physics synopsis: http://ift.tt/2khHRxy

The post Quantum: ORNL Sets Data Density Transmission Record appeared first on HPCwire.

via Government – HPCwire

[venitisblr-blog]

SUPERDENSE CODING OVER OPTICAL FIBER

SUPERDENSE CODING OVER OPTICAL FIBER

Sending quantum bits can potentially be twice as efficient as sending classical bits. But realizing this so-called superdense coding has been a major challenge. Brian Williams and colleagues from Oak Ridge National Laboratory, Tennessee, have sent quantum bits over a small fiber link, achieving a new record in bit density. Their technique utilizes the hyperentanglement of photon pairs���a combined…

[qutronics]

via QuNews

[qutronics]

via QuNews

[qutronics]

via QuNews

[qutronics]

via QuNews

[qutronics]

via QuNews

[qutronics]

via QuNews

[qutronics]

via QuNews

[qutronics]

via QuNews

[qutronics]

via QuNews

[qutronics]

via QuNews