In our determination to ‘follow the science’ we have abandoned all logic

The latest announcement on travel and Covid has, I confess, left me confused. It appears that someone from overseas, with documents proving they have been double-vaccinated with a reliable covid vaccine, may enter the UK without having to quarantine, providing they test negative. UK citizens, on the other hand, must still self-isolate at the first ping of their test and trace app, even if they have already had two jabs. ‘The science’, we are told, means this will remain the case until 16  August. In short – we are happy to accept the certification of vaccination for a foreign country, but not our own. 

Meanwhile, the overseas travel traffic light system changes so frequently that it’s often confusing. This week, we were told that France had to return to an ‘amber plus’ rating, which obliges all arrivals from France to go into quarantine, supposedly due to a higher prevalence of

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An efficient two-bit quantum logic gate has been out of reach, until now — ScienceDaily

Research from the McKelvey School of Engineering at Washington University in St. Louis has found a missing piece in the puzzle of optical quantum computing.

Jung-Tsung Shen, associate professor in the Preston M. Green Department of Electrical & Systems Engineering, has developed a deterministic, high-fidelity two-bit quantum logic gate that takes advantage of a new form of light. This new logic gate is orders of magnitude more efficient than the current technology.

“In the ideal case, the fidelity can be as high as 97%,” Shen said.

His research was published in May 2021 in the journal Physical Review A.

The potential of quantum computers is bound to the unusual properties of superposition — the ability of a quantum system to contain many distinct properties, or states, at the same time — and entanglement — two particles acting as if they are correlated in a non-classical manner, despite being physically

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Taproot: An Example Of Bitcoin’s Win-Win Logic

Taproot has a variety of benefits for all users of Bitcoin, and is an example of improving ability to expand and enhance Bitcoin.

Jason Lau is the COO of Okcoin.

Almost four years after Bitcoin’s last big update, Taproot is finally locked in and will activate in November. This is a big win for Bitcoin and the entire ecosystem, whether or not you understand the technical intricacies of the upgrade itself. Okcoin will support Taproot when it activates, to ensure that our customers and the network can benefit.

Taproot is a win for everyday users because it will make transactions cheaper: switching from the current standard (ECDSA) to Schnorr signatures will make transactions about 12% more efficient. It is also going to make smart contracts cheaper, by requiring fewer signatures to be broadcast to the blockchain. More efficient block space usage is going to benefit everyone.

Taproot is a win

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Survey Of Simple Logic Simulators

A few months ago, a tweet by [Ken Shirriff] asking about simple digital simulators caught my attention. The topic came up again in May when a repair video by [CuriousMarc] featured one such simulator called Logisim-evolution. It made me want to take a fresh look on what’s out there and which features set the different simulators apart.

So today, let’s take a quick survey of a few such simulators that I found. I’m focusing on plain logic simulators, analyzing ones and zeros using Boolean logic. They are not doing SPICE-like analog analysis of transistor logic gates, but they’re still quite handy for proofing out designs.


Logicsim from 1983 is the oldest one on our list, developed by Wun Chin Kau and Douglas Jones in support of computer science lab classes at the University of Iowa Computer Science department. It is a text-based simulator, open source for personal and

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