Quantum switches are prepared for real-world testing in Chicago

Earlier this month, a group of research laboratories in Chicago a statement A quantum network stretching 124 miles long stretches from the suburb of Lemont, through the city of Chicago, to Hyde Park and back. This total length represents a newly added 35-mile segment of optical fiber that was recently connected to an 89-mile quantum loop at the US Department of Energy’s Argonne National Laboratory. Launched in 2020linking labs from the Chicago Quantum Exchange and the University of Chicago.

The goal of building such a network is to enable researchers to experiment with new types of quantum communications, security protocols, and algorithms with the goal of progressing toward an initial stage. quantum internet (Which could sound pretty good as an early version of classic internet). Currently, Toshiba is using it to test their distribution Quantum encryption keys In an environment factors such as noise, weather, and temperature fluctuations are faced in order to understand how powerful this method is, and what potential problems may arise.

So far, researchers have been able to send information at a speed of 80,000 quantum bits (or qubits – more on what’s below) per second. These kinds of experimental switches can be useful in the future as powerful quantum computers Threatens to break classic encryption, a problem that has been highlighted Legislators in Congress.

As larger quantum computers begin to emerge, researchers are actively exploring ways to use the laws of quantum physics to create a communication channel that is resistant to tampering and hacking. This kind of communication channel could also become a way to “connect” quantum devices together.

“Let’s say you have a 1,000-qubit quantum computer. And here you have another 1,000-qubit computer. You want to connect them together the same way we build supercomputers today by creating clusters, but you can’t just connect computers using classic wires,” he says. “You need a quantum wire to preserve the quantum states of both machines.” David Oshalom, a professor at the University of Chicago and chief scientist at Argonne National Laboratory. without entering the classical world.”

Chicago now has a quantum network 124 miles long.  That's what it is.
An illustration of the current quantum network. University of Chicago

Investigating the possibilities of quantum communication

Because this is the quantum world, things work a little differently. To start, for things to show quantitative qualities, they must be either very cold or very small. Chicago chose small.

“Many commercially available quantum machines today are usually superconductors, so the temperatures in them must be very low,” Oshalom says. “Quantum communication uses photons, and the polarization of light encodes information.” This means that the network can be operated at room temperature.

Using photons means they can also use the optical fibers through which classical communications flow today. But here the problems begin to appear. Optical fibers are made of thin strands of glass, and glass has flaws. When single photons or light pulses travel down, they can go a little smoothly, but over time and distance, the amplitude of the signal diminishes because the light dissipates impurities. For the classic internet, the solution is repeaters. These are thumb-sized devices that are placed every 50 miles or so to amplify and transmit the signal.

The quantum world has hard rules. Quantum bits (qubits), unlike conventional bits, are not either 0 or 1. They are a superposition of the two, meaning they can be either 0, 1 or both at the same time. You might see a qubit depicted as a sphere with an arrow emerging from its center. You cannot copy the case of a quantity (see file The theory of non-reproduction), looking at it or noticing it pulls it out of the overlay, so you’re destroying qubits. (The advantage this brings is that it makes quantum bonds tamper-proof.)

[Related: NASA is launching a new quantum entanglement experiment in space]

A quantum signal can still traverse distances in a city through fibers without a repeater. However, for the future, there are some ideas to expand its range. The first is to go through the air to a satellite, and then back (that’s what Researchers do in China). But in the air, light can also be absorbed by moisture, and not many photons return to Earth (NASA is trying to see if they can Stability improvement intertwined in space). With optical fibers, you can tune the signal, you can know where it is, and you can send multiple frequencies of signals at the same time. In addition, you can take advantage of the existing infrastructure. Oshalom envisions that a future quantum network will benefit from both fiber and satellite communications, and possibly short-distance fibers, and longer-distance satellites.

Another idea is to use a trick called tangle swap. This is where the various nodes run (the Chicago network currently has six nodes). Nodes do not refer to a super-quantum computer containing hundreds of qubits. In most cases, it is a kind of quantum memory, which Oshalom likens to a small and simple quantum computer. You can enter the information and you can take it out.

“Let’s say I can hardly get [quantum] remind you. You want to send it to someone else somewhere else. But we don’t have a repeater.” “What you might be able to do is take the tangled information without looking at what it is, put it in memory and then you can swap it out for something else.”

How do quantum keys work

Creating quantum keys to encrypt information is a practical application of quantum communication through entanglement. Entangled particles behave as if they were connected regardless of the distance between them. This means that if you look at one particle, it will change the other, and if you look at both particles, their measurements will be related. Once you have created the entanglement, distributed the state of the entanglement, and maintained it over distance and time, you can use this property to transmit information instantly.

Classic keys, which act like ciphers for information, are generated from algorithms to encrypt information and make it secure. These algorithms usually have a mathematical function that can be easily solved in one direction, but it is difficult (though not impossible) to reverse geometry.

“It’s really hard to make keys that are not tampered with, that you can’t work backwards and figure out how to create keys, or that it’s hard to stop people from copying the key,” Oshalom says. “And you don’t know if someone copied it.”

[Related: IBM’s massive ‘Kookaburra’ quantum processor might land in 2025]

A quantum key is generated by quantum mechanics, and the key pair that is distributed between the transmitter and receiver are closely linked through quantum entanglement. In the Chicago experiment, quantum switches are sent via photons whose properties (through factors such as polarization directions) have been modified to encode the qubits. No one can copy or intercept the key without damaging the quantum information.

Quantum keys can consist of a series of quantum bits. “A quantum key is a function of the base state. You have a coordinate system to read it in,” explains Oshalom. “Your” and “bit” are interrelated. So it is very different from a classical key. If someone jams your key they will scramble for me. I can also be sure that you received it, Depending on how I received my key.”

New technology test

The quantum field, despite all the hype, is still in its infancy. This means that researchers do not know for sure what will work well and what will not. Part of how this mystery is investigated through this network is the fact that different nodes in different labs across Chicago are all experimenting with different strategies. “For example, we currently have a cold atom lab as one of the nodes, so you can actually take the quantum communication information, put it into a simple trapped atom, and then extract it,” Oshalom says. His lab, another node in the network, is working to integrate magnetic atoms from the periodic table to store and transmit quantum information. Another laboratory working with superconductors. “Each node is designed to amplify different technological ideas,” he says.

They also plan to open this network to outside researchers and companies who can come in, connect and test their prototype devices and detectors and get them up and running.

Quantum switches are just the beginning when it comes to distributed entanglement capabilities. “There is a lot you can do when you think about distributing information differently,” Oshalom says, with a global sense of the environment as one example. “Today we probe the world with mostly classic sensors, but the world is quantum mechanical. It begs the question – what don’t we see just because we’ve never looked? Between these sensing technologies and a way to assemble sensors, I’m optimistic we’ll learn a lot.”