Quantum computing: Hype or reality? OVH says businesses would be better off prepared Euro cloud biz OVH recently announced the purchase of its first quantum-powered system as part of long-term plans to build a quantum environment for developers and other users. The company has a pragmatic approach, viewing it as a technology that has a long way to go before it will live up to the hype, but nevertheless …
For most businesses, planning for quantum computing will I suspect be more of a cybersecurity issue. At some point in the not too distant future it will be economically viable to start brute force decrypting what is currently strongly encrypted data using quantum techniques. Crucially it will be possible to do so within a useful timeframe - for example where the target is still in business / alive in order to blackmail or prosecute them.
Crooks and spooks are right now hoovering up encrypted traffic in anticipation of being able to decrypt it quickly whilst it is still useful to them.
Nobody is giving a date for when quantum computing will be able to deliver this, but it is definitely a case of when, not if, and it could be in the next few years. When it happens it will be sudden, and I imagine catastrophic.
You could start trying to brute-force decryption now by conventional means. The only criteria to decide whether to do that are the cost and the likelihood of the result being useful when you get it and the "when" starts now. That will still be the case if you wait for quantum decryption. What's more, if you've already got the data the "when" still starts now. You have to work out whether a slow ongoing process will take longer than a long wait and a quick process. I don't suppose either process will be cheap.
Even if it is the future, this seems to be like learning how to use the Babbage Difference Engine because you think classical computers are going to be the next big thing.
You would have been right in your assessment, but very little of the skills you would have learned from operating one of those would be relevant to what it actually developed into.
My understanding is that every quantum decision creates a new universe. I'm ignoring the various laws of thermodynamics and assuming the energy for this just appears magically from somewhere. OK so Schrodinger wants his cat back alive so all I have to do is find one of the universes where the box contains a live cat. How do I know what colour cat I'm going to find in the box?
Moving on to the fabled decryption of encrypted data by one of these miracle quantum computers how do I know I picked the right universe? After all with an infinity of universes I'm sure there are many where the data will decrypt and seem to make sense even if its wrong for this universe.
Someone in the IT Industry working for a new technology actually saying....."look it might do some of the stuff you want and won't do a lot of the stuff that you think you want. Do some research"
As opposed to "CLOUD! CLOUD! CLOUD! AI! AI! AI! AI!"
Just wait until the marketing people get involved :(
I saw a talk from our local QC expert (University of Copenhagen) about the Quantum Fourier Transform (QFT), which is the basis for pretty much all of the algorithms that can break encryption in polynomial time on a QC, as well as quantum chemistry algorithms. After presenting the algorithm, he talked about it limitations with respect to realistic quantum computers. Specifically:
1. QFT needs perfect qubits (never gonna happen) or strong error-correction, which means around 1000 realistic qubits for each error-correcting cubit, so we need around a million realistic qubits. Currently, we are about 100 of those.
2. We need rotation of a quantum state in complex-number hypersphere to a precision of better than 1/2^n parts of a full rotation (for n-bit numbers). Currently, we are around 1/2³, and we might reach 1/2⁴ in a couple of years. 1/2²⁵⁶ will not happen in the next 50 years (if ever), and by then strong encryption will use many more bits.
3. We need quantum computers that can sustain a superposition for thousands of complex operations. We are currently at a few hundred single-qubit operations and a few dozen two-cubit operations (specifically, controlled negation).
4. Qubits can only interact with their nearest neighbours (in a square or hexagonal grid), and to bring cubits that need to interact next to each other, we need a lot of swaps. A swap can be done using three controlled negations, so we can do less than 10 of those currently.
So, while quantum computers _may_ become useful for very specialised purposes, it will IMO never break strong encryption. Quantum superposition can, however, itself be used for secret communication, but that isn't really quantum computing.
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