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Category: quantum physics – Page 57

Robotic eyes mimic human vision for superfast response to extreme lighting

In blinding bright light or pitch-black dark, our eyes can adjust to extreme lighting conditions within a few minutes. The human vision system, including the eyes, neurons, and brain, can also learn and memorize settings to adapt faster the next time we encounter similar lighting challenges.

In an article published in Applied Physics Letters, researchers at Fuzhou University in China created a machine vision sensor that uses quantum dots to adapt to extreme changes in light far faster than the human eye can—in about 40 seconds—by mimicking eyes’ key behaviors. Their results could be a game changer for robotic vision and autonomous vehicle safety.

“Quantum dots are nano-sized semiconductors that efficiently convert light to ,” said author Yun Ye.

Quantum translator on a chip: This device converts microwaves to light

Imagine if future quantum computers could talk to each other across cities, countries, even continents without losing their spooky quantum connection. A team of researchers from the University of British Columbia (UBC) has created a device that could help us realize this future.

This device, which is just a tiny chip made of silicon, works like a universal translator, converting signals between two incompatible energies: microwaves and light. This chip can convert up to 95% of a quantum signal in both directions, and with almost zero noise.

Quantum computer simulates spontaneous symmetry breaking at zero temperature

For the first time, an international team of scientists has experimentally simulated spontaneous symmetry breaking (SSB) at zero temperature using a superconducting quantum processor. This achievement, which was accomplished with over 80% fidelity, represents a milestone for quantum computing and condensed matter physics.

The results are published in the journal Nature Communications.

The system began in a classical antiferromagnetic state, in which particles have spins that alternate between one direction and the opposite direction. It then evolved into a ferromagnetic quantum state, in which all particles have spins that point in the same direction and establish quantum correlations.

Terahertz instead of gigahertz — quantum material speeds up transistor switching by 1000 times

Researchers from Northeastern University in the United States have found a way to speed up electronics by a thousand times by replacement of silicon chips on quantum materials.

It is noted, that the new technology, through controlled heating and cooling, allows the quantum material to switch between the state of a conductor and an insulating material almost instantly. According to the researchers, such materials can replace silicon and lead to the emergence of electronic devices that are much faster and smaller.

«Processors currently operate in gigahertz. The speed of change that this will provide will allow you to move to terahertz», — explains the lead author of the study, professor of physics Alberto de la Torre.

Quantum Dots For Reliable Quantum Key Distribution

Making the exchange of a message invulnerable to eavesdropping doesn’t strictly require quantum resources. All you need to do is to encrypt the message using a one-use-only random key that is at least as long as the message itself. What quantum physics offers is a way to protect the sharing of such a key by revealing whether anyone other than sender and recipient has accessed it.

Imagine that a sender (Alice) wants to send a message to a recipient (Bob) in the presence of an eavesdropper (Eve). First, Alice creates a string of random bits. According to one of the most popular quantum communication protocols, known as BB84, Alice then encodes each bit in the polarization state of an individual photon. This encoding can be performed in either of two orientations, or “bases,” which are also chosen at random. Alice sends these photons one at a time to Bob, who measures their polarization states. If Bob chooses to measure a given photon in the basis in which Alice encoded its bit, Bob’s readout of the bit will match that of Alice’s. If he chooses the alternative basis, Bob will measure a random polarization state. Crucially, until Alice and Bob compare their sequence of measurement bases (but not their results) over a public channel, Bob doesn’t know which measurements reflect the bits encoded by Alice. Only after they have made this comparison—and excluded the measurements made in nonmatching bases—can Alice and Bob rule out that eavesdropping took place and agree on the sequence of bits that constitutes their key.

The efficiency and security of this process depend on Alice’s ability to generate single photons on demand. If that photon-generation method is not reliable—for example, if it sometimes fails to generate a photon when one is scheduled—the key will take longer to share. If, on the other hand, the method sometimes generates multiple photons simultaneously, Alice and Bob run the risk of having their privacy compromised, since Eve will occasionally be able to intercept one of those extra photons, which might reveal part of the key. Techniques for detecting such eavesdropping are available, but they involve the sending of additional photons in “decoy states” with randomly chosen intensities. Adding these decoy states, however, increases the complexity of the key-sharing process.

Quantum protocol achieves Heisenberg-limited measurement precision with robust spin states

Researchers from the National University of Singapore (NUS) have achieved exciting progress in quantum metrology, a field that harnesses quantum effects to make measurements with unprecedented accuracy. Their newly developed protocol could potentially benefit emerging technologies such as navigation and sensing of extremely weak signals.

Quantum metrology exploits the unique properties of to achieve sensitivities far exceeding classical limits. Pushing beyond the so-called standard quantum limit (SQL) to reach the ultimate Heisenberg limit (HL) typically requires highly entangled quantum states, such as Greenberger–Horne–Zeilinger (GHZ) states. However, these states are extremely challenging to generate, maintain, and measure, as they are highly susceptible to and readout errors, which are major obstacles for practical deployment.

Led by Professor Gong Jiangbin from the Department of Physics at the NUS Faculty of Science, the research team has developed a novel strategy that eliminates these roadblocks. Their method leverages quantum resonance dynamics in a periodically driven spin system, a well-studied model called the quantum kicked top.

Photon ‘time bins’ and signal stability show promise for practical quantum communication via fiber optics

Researchers at the Leibniz Institute of Photonic Technology (Leibniz IPHT) in Jena, Germany, together with international collaborators, have developed two complementary methods that could make quantum communication via fiber optics practical outside the lab.

One approach significantly increases the amount of information that can be encoded in a ; the other improves the stability of the quantum signal over long distances. Both methods rely on standard telecom components—offering a realistic path to secure through existing fiber networks.

From hospitals to government agencies and industrial facilities—anywhere must be kept secure—quantum communication could one day play a key role. Instead of transmitting electrical signals, this technology uses individual particles of light—photons—encoded in delicate quantum states. One of its key advantages: any attempt to intercept or tamper with the signal disturbs the , making eavesdropping not only detectable but inherently limited.

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