Imagine a world where information can be transmitted securely across the globe, free from the prying eyes of hackers. Its incredible power lies in the realm of quantum mechanics, making it a groundbreaking advancement with immense potential for the future of telecommunications. There have been obstacles to conquer, but there has also been notable progress, exemplified by a recent achievement from researchers at Harvard University.

Using the existing fiber optics within the city of Boston, the team successfully demonstrated the longest transmission between two nodes. The fiber path covered a total distance of 35 kilometers (22 miles), encircling the entire city. The two nodes that connected to the close path were situated on different floors, making the fiber route not the shortest but rather an intriguing one.

Quantum information has been successfully transmitted over longer distances, showcasing remarkable advancements in this experiment that bring us closer to the realization of a practical quantum internet. The real breakthrough lies in the nodes, going beyond the mere utilization of optical fibers.

A typical network utilizes signal repeaters made of optical fiber. These devices incorporate optical receivers, electrical amplifiers, and optical transmitters. The signal is received, transformed into an electrical form, and subsequently converted back into light before being transmitted. They play a crucial role in expanding the reach of the original signal. And in its present state, this is not suitable for quantum internet.

The issue lies not in the technology, but rather in the fundamental principles of physics. Copying quantum information is not possible in that manner. Quantum information is highly secure due to its entangled state. The Harvard system operates by utilizing individual nodes that function as miniature quantum computers, responsible for storing, processing, and transferring information. This quantum network, consisting of only two nodes, is currently the most extensive one ever achieved, with nodes capable of such remarkable functionality.

“Demonstrating the ability to entangle quantum network nodes in a bustling urban environment is a significant milestone in enabling practical networking between quantum computers,” stated Professor Mikhail Lukin, the senior author.

At each node, a tiny quantum computer is constructed using a small piece of diamond that contains a flaw in its atomic arrangement known as a silicon vacancy center. At temperatures close to absolute zero, the silicon vacancy has the remarkable ability to capture, retain, and interconnect pieces of data, making it an ideal choice for a node.

“Given the existing entanglement between the light and the first node, it has the capability to transmit this entanglement to the second node,” elucidated Can Knaut, a graduate researcher in Lukin’s lab. “This phenomenon is known as photon-mediated entanglement.”

The study has been published in the prestigious journal Nature.

Imagine yourself engaged in your own affairs, seated on a park bench, gazing at your mobile device. Explosion. An individual seizes your device and swiftly flees with it. While Android and iOS devices do have certain security measures, what about the brief period of time when the phone is still unlocked? Is there a method available to remotely erase its data?

Burglars can obtain a substantial amount of information within that brief duration. Each moment is significant. During the Google I/O 2024 developer conference, Google unveiled a new feature for Android called Theft Detection Lock. This feature is specifically designed to safeguard against the increasing risk of theft. Once activated, the AI-driven function will automatically secure the device.

According to Google, if your phone detects a typical movement related to theft, it will rapidly lock the screen to prevent thieves from easily accessing your data. An instance of such a stimulus is a mechanism that abruptly initiates rapid motion in the opposite direction.

Google is implementing an offline device lock feature, specifically designed to safeguard the device in the event of intentional disconnection from the network. Occurrences such as consistently failing to authenticate the phone will activate that functionality.

The forthcoming update will also introduce functionality that enhances the level of difficulty for malefactors attempting to perform a remote factory reset on your device. According to Google, this upgrade prevents thieves from setting up a stolen device again without having knowledge of your device or Google account credentials, even if they force a reset. By rendering a stolen device unsellable, it diminishes the motivation for individuals to engage in phone theft.

Biometric authentication will be mandatory for modifying sensitive information while the device is connected from an unsecured location.

Based on papers published at the same time by unrelated teams, two methods for improving capacitors’ ability to store charge appear to be effective. Each has the potential to make supercapacitors better at storing energy and maybe even put them in the running for large-scale energy storage.

For a long time, supercapacitors have been better than batteries because they can quickly release the charge they have stored. But not even the best supercapacitors have been able to store enough power to meet the most important needs of society. Sometimes, big steps forward have made supercapacitors look like they could compete in that market. But since lithium-ion battery prices have dropped so much, there isn’t much room for other batteries. That could change soon.

Two papers that came out last month in the same issue of Science both look at big improvements in capacitance. It remains to be seen if either of them can be scaled up, though.

The basic idea behind all capacitors is the same. There is material between the positive and negative charges to keep them from jumping across the gap. When a switch is closed, the negative charges can move around to meet the positive charges. This makes an electric current, which can be used for many things.

Laptops and phones now have hundreds of capacitors inside them. When you look at a phone, you can tell how small it is. Because of this, the amount of power they can store is many times too small to power a car, let alone a city all night.

As you might guess from their name, supercapacitors have a lot more capacitance. Even though they’ve made regenerative braking possible, batteries are still the best choice for long-distance driving. To make that happen, the capacitance has to go up, which means finding cheap materials that stop very large amounts of charge from recombining.

Many capacitors use ferroelectric materials like BaTiO3, but they have a problem called “remnant polarization,” which means that some charge stays behind instead of being released. Their crystals also break down over time.

A team from Korean and American institutions reduced remnant polarization by putting a 3D structure between 2D crystals. They were then able to store 191.7 joules per cubic centimeter of capacitor and release it with more than 90% efficiency. Similar products on the market today can store around 10 joules per cubic centimeter.

Dr. Sang-Hoon Bae of Washington University in St. Louis said in a statement, “We made a new structure based on the innovations we’ve already made in my lab involving 2D materials.” “At first, we weren’t interested in energy storage, but while we were studying the properties of materials, we came across a new physical phenomenon that we thought could be used for energy storage. It was very interesting and could be much more useful.”

The work report by Bae and his co-authors only talks about testing the capacitor over 10 cycles, which shows that there is still a long way to go before it can be used in real life. “We’re not quite at our best yet, but we’re already doing better than other labs,” Bae said. For capacitors to be able to charge and discharge very quickly and hold a lot of energy, our next step is to improve the structure of this material even more. To see this material used widely in big electronics like electric cars and other new green technologies, we need to be able to do that without losing storage space over time.

In the same issue of Science, scientists from Cambridge University talk about results that change how people think about making supercapacitors with carbon electrodes store more power. They say, “Pore size has long been thought to be the main way to improve capacitance.” But when commercial carbons with pores measuring nanometers were compared, there wasn’t much of a link between size and capacitance. With nuclear magnetic resonance spectroscopy, we can see that what matters is the level of structural disorder in the capacitors’ domains.

They say that more disorganized carbons with smaller graphene-like domains have higher capacitances because their nanopores store ions more efficiently. “We think that for carbons with smaller domains, the charges are more concentrated, making the interactions between ions and carbon atoms stronger. This makes it easier for ions to be stored.”

The paper makes no mention of how much capacitance is possible when the carbon domains are sufficiently disorganized. This is because it goes against the norm to try to make electronic devices more disorganized than ordered.