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“Revolutionizing Quantum Communication: Nanophotonic Platform Boosts Efficiency of Nonlinear-Optical Quantum Teleportation”

Researchers have long recognized that quantum communication systems would transmit quantum information more faithfully and be impervious to certain forms of error if nonlinear optical processes were used. However, past efforts at incorporating such processes could not operate with the extremely low light levels required for quantum communication.

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The scientists have been working on incorporating nonlinear optical processes into quantum communication systems for a long time. These processes can transmit quantum information more faithfully and be impervious to certain forms of error. However, past efforts at using such processes were hindered by their inability to operate with the extremely low light levels required for quantum communication.

A team at the University of Illinois Urbana-Champaign has now improved this technology by basing the nonlinear process on an indium-gallium-phosphide nanophotonic platform. The result is substantially more efficient than prior systems, requiring much less light and operating all the way down to single photons, the smallest unit of light.

The researchers’ achievement demonstrates the power of quantum communication with nonlinear optics. Their system transmits quantum information with 94% fidelity compared to the theoretical limit of 33% on systems using linear optical components. This means that their technology is promising, and it has the potential to be used in other areas of quantum communications.

Transmission of quantum information over networks is facilitated by the quantum teleportation protocol. In this process, the phenomenon of quantum entanglement is exploited to transfer quantum information between a sender and a receiver without transmitting it through a communication channel. The advantage of this procedure is that the influences of external noise and channel imperfections are greatly mitigated.

However, there are two factors which limit the performance of quantum teleportation. First, the use of standard, linear optical components introduces inherent ambiguities in the transmission. Second, the entangled photons are made with an imperfect process subject to errors and excess noise. In particular, it is common for entanglement sources to produce more than a single pair of photons at once, making it unclear whether the two used in teleportation are truly entangled.

The researchers have now found a solution to this problem by using nonlinear optical components. These cause photons of different frequencies to combine and create new photons at new frequencies. For quantum teleportation, the nonlinear process used is “sum frequency generation” (SFG), in which the frequencies of two photons add to form a new photon.

When SFG is used in quantum teleportation, the protocol does not proceed if two photons of the same frequency are detected. This filters out the primary type of noise in most entangled photon sources and allows for much higher teleportation fidelities than would be possible otherwise. However, the main drawback is that an SFG conversion occurs with very low probability, making the teleportation process highly inefficient.

The researchers have now overcome this challenge by using a nanophotonic platform, which has increased the efficiency of the nonlinear optical components. They achieved a factor of 10,000 increase in conversion efficiency to 1 in 10,000. This breakthrough has the potential to revolutionize quantum communication and make it more efficient.

The researchers are optimistic that their technology will be used in other areas of quantum communications, including entanglement swapping. With further development, they believe that quantum teleportation with nonlinear optical components can be made even more efficient.

Artificial Intelligence

Riding the Tides: Scientists Develop Simple Algorithm for Underwater Robots to Harness Ocean Currents

Engineers have taught a simple submarine robot to take advantage of turbulent forces to propel itself through water.

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Researchers at Caltech have made a breakthrough in developing a simple algorithm for underwater robots to harness the power of ocean currents. Led by John Dabiri, the Centennial Professor of Aeronautics and Mechanical Engineering, the team has successfully created a system that allows small autonomous underwater vehicles (AUVs) to ride on turbulent water currents rather than fighting against them.

The researchers began by studying how jellyfish navigate through the ocean using their unique ability to traverse and plumb the depths. They outfitted these creatures with electronics and prosthetic “hats” to carry small payloads and report findings back to the surface. However, they soon realized that jellyfish do not have a brain and therefore cannot make decisions about how to navigate.

To address this limitation, Dabiri’s team developed what would be considered the equivalent of a brain for an AUV using artificial intelligence (AI). This allowed the robots to make decisions underwater and potentially take advantage of environmental flows. However, they soon discovered that AI was not the most efficient solution for their problem.

Enter Peter Gunnarson, a former graduate student who returned to Dabiri’s lab with a simpler approach. He attached an accelerometer to CARL-Bot, an AUV developed years ago as part of his work on incorporating artificial intelligence into its navigation technique. By measuring how CARL-Bot was being pushed around by vortex rings (underwater equivalents of smoke rings), Gunnarson noticed that the robot would occasionally get caught up in a vortex ring and be propelled clear across the tank.

The team then developed simple commands to help CARL-Bot detect the relative location of a vortex ring and position itself to catch a ride. Alternatively, the bot can decide to get out of the way if it does not want to be pushed by a particular vortex ring. This process involves elements of biomimicry, mimicking nature’s ability to use environmental flows for energy conservation.

Dabiri hopes to marry this work with his hybrid jellyfish project, which aims to demonstrate a similar capability to take advantage of environmental flows and move more efficiently through the water. With this breakthrough, underwater robots can now ride the tides, reducing energy expenditure and increasing their efficiency in navigating the ocean depths.

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Communications

A Breakthrough in Carbyne Synthesis: Unlocking Its Potential in Next-Generation Electronics

Carbyne, a one-dimensional chain of carbon atoms, is incredibly strong for being so thin, making it an intriguing possibility for use in next-generation electronics, but its extreme instability made it nearly impossible to produce at all, let alone produce enough of it for advanced studies. Now, an international team of researchers may have a solution.

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The synthesis of carbyne, a one-dimensional chain of carbon atoms, has long been a challenge due to its extreme instability. However, an international team of researchers has finally found a solution by enclosing it within single-walled carbon nanotubes. This breakthrough opens up new possibilities for using carbyne in next-generation electronics.

The researchers used a special precursor, ammonium cholate, to grow carbyne at low temperatures. They also employed single-walled carbon nanotubes as a protective shell around the carbyne, which helps keep it stable. The new synthesis method produces more carbyne than before, making it easier for scientists to study its properties and explore its potential applications.

The unique properties of carbyne make it an attractive material for next-generation electronics. Unlike graphene, carbyne has a built-in semiconductor gap, allowing it to act as a switch for electrical current. This property makes carbyne-based electronics potentially faster and more efficient than today’s silicon-based technology.

The research team also made an unexpected discovery during the study. They found that a common solvent, cholate, can transform into carbyne chains without additional complex steps. This finding shows how familiar materials can take on new roles in advanced chemistry.

While many questions about carbyne remain unanswered, this breakthrough is a significant step forward. With a stable way to produce carbyne in larger quantities, researchers can now explore its potential more deeply and potentially unlock new technologies in the field of next-generation electronics.

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Computers & Math

“Revolutionizing Superconductivity: 3D Nanostructures Pave the Way for Reconfigurable Devices”

An international team has pioneered a nano-3D printing method to create superconducting nanostructures, leading to groundbreaking technological advancements.

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A groundbreaking study has successfully created three-dimensional superconducting nanostructures, akin to a nanoscale “3D printer.” This achievement opens doors to unprecedented control over the superconducting state, enabling researchers to switch it on and off in different parts of the structure by rotating it in a magnetic field.

The research team, led by scientists at the Max Planck Institute for Chemical Physics of Solids, has demonstrated the creation of complex 3D geometries at the nanoscale, a feat that was previously considered impossible. This breakthrough has significant implications for the development of new superconducting technologies and devices.

Superconductors are materials that can exhibit zero electrical resistance and expel magnetic fields. The formation of Cooper pairs – bound pairs of electrons that move coherently through the material without scattering – is responsible for this striking behavior. However, controlling this state at the nanoscale has proven to be a significant challenge, hindering the exploration of novel effects and future technological developments.

The researchers involved in this study have successfully localized control over the superconducting state by patterning superconductors in 3D nanogeometries. This achievement has enabled them to create reconfigurable superconducting devices that can switch on and off in different parts of the structure, simply by rotating it in a magnetic field.

The implications of this breakthrough are far-reaching, offering a new platform for building adaptive or multi-purpose superconducting components. The ability to propagate defects of the superconducting state also opens the door to complex superconducting logic and neuromorphic architectures, setting the stage for a new generation of reconfigurable superconducting technologies.

This study has been published in the journal Advanced Functional Materials and represents a significant step forward in the field of nanotechnology. The researchers involved have demonstrated their ability to push the boundaries of what was previously thought possible, paving the way for further innovations and discoveries.

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