There are exactly 2 reasons we might want quantum networks.
1. 100% secure communication channels (even better we can detect any attempt at eavesdropping and whatever information is captured will be useless to the eavesdropper)
2. Building larger quantum computers. A high fidelity quantum network would allow you to compute simultaneously with multiple quantum chips by interfacing them.
The thing that makes quantum networking different from regular networking is that you have to be very careful to not disturb the state of the photons you are sending down the fiber optics.
Im currently doing my PhD building quantum networking devices so im a bit biased but I think it’s pretty cool :).
Now does it matter I’m not sure. Reason 1 isn’t really that useful because encryption is very secure. However if quantum computers start to scale up and some encryption methods get obsoleted this could be nice. Also having encryption that is provably secure would be nice regardless.
Reason 2 at the moment seems like the only path to building large scale quantum computing. Think a datacenter with many networked quantum chips.
Something about this new iteration of phrenology seems more insidious. It allows researchers to avoid having to make actual claims about relationships between structure and outcome. Instead the buck is passed to the models. The scientists are free to just report their model accuracy and leave the conclusion of the validity of the connection to the reader. This is very abuseable too as bad methods can easily create convincing results that support a desired narrative. Oh well just another thing to worry about in the future.
Oh also to clarify: What exactly is the device they have made? Well it's pretty complicated but one handwavey explanation is that they have created a device that splits an electron into two quasiparticles and does computations by physically moving these quasiparticles around each other. This is what they refer to as braiding.
Some background for the unfamiliar. This is a new type of quantum computing platform that Microsoft has been pursuing almost independently. Most major research groups focus on superconducting qubits (IBM, Google) or trapped atoms/ions, (or photonics, or a lot of other things) while Microsoft has been developing topological qubits. These qubits are particularly interesting because they exhibit a natural resilience to noise that all other qubit systems lack. However, creating them has been a major challenge.In the summer of 2022, Microsoft claimed for the first time to have created a such qubit, though their results were met with some skepticism.
Now, it seems there is no longer any debate. Microsoft has successfully created and controlled topological qubits. Is this a big deal? Yes but its a far cry from a million qubits. Fair warning, this is not my area of research, so I'm unsure what developments occurred between their 2022 results and now. The relevant papers from Microsoft can be found here:
https://www.nature.com/articles/s41586-024-08445-2https://arxiv.org/abs/2502.12252
edit:
I read the nature paper more carefully, it looks like it is still up for debate whether they have made a topological qubit, but the evidence today is considerably stronger than previous results. Anyways don't start worrying about microsoft hacking your bank account just yet.
Quantum mechanics tells us that the qubit (coin) can exist in any linear superposition of heads and tails. To express this you write a|heads> + b|tails> the only constraint is that a^2 + b^2 must equal 1. Now why would that be the constraint? It is because a^2 and b^2 are the probabilities of measuring heads and tails respectively.
In this example the coin is put into the state where an and b equal 1/sqrt(2) to give an equal probability of each outcome. So there is exactly one state associated with the coin. Now this state does lead to two possible outcomes but the underlying state (that can not be directly observed) is exactly one thing.