I recommend this book: Q is for Quantum https://www.amazon.co.uk/dp/0999063502?ref=ppx_pop_mob_ap_share https://www.amazon.co.uk/dp/0999063502?ref=ppx_pop_mob_a

I recommend this book: Q is for Quantum https://www.amazon.co.uk/dp/0999063502?ref=ppx_pop_mob_ap_share https://www.amazon.co.uk/dp/0999063502?ref=ppx_pop_mob_ap_sh... Direct answer, QC's are shown to exist at some scale in our universe. They may not get larger than 1000 qbits, but they also might. However so far the most practical thing that QC has done is inspire new classical algorithms for some problems, notably in recommendation.