Q-Day
PostQuantum.com – Industry news and blog on Quantum Computing, Quantum Security, PQC, Post-Quantum, Q-Day, Y2Q
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Capability D.2: Decoder Performance (Real‑Time Error Correction Processing)
In a fault-tolerant quantum computer, qubits are continuously monitored via stabilizer measurements (producing “syndrome” bits) to detect errors. The decoder is a classical algorithm (running on specialized hardware) that takes this rapid stream of syndrome data and figures out which qubits have experienced errors, so that corrections can be applied…
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Capability C.2: Magic State Production & Injection (Non-Clifford Gates)
Magic states are an essential “extra ingredient” for universal quantum computing, often metaphorically likened to a magic catalyst enabling otherwise impossible operations. Quantum algorithms require not only robust qubits and error correction, but also a way to perform non-Clifford gates - operations outside the easy Clifford group. These non-Clifford gates…
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Capability C.1: High-Fidelity Logical Clifford Gates
Cryptographically Relevant Quantum Computers (CRQCs) will rely on a suite of core capabilities - and high-fidelity logical Clifford gates are among the most essential. This capability refers to performing the fundamental set of quantum logic operations (the Clifford gates: Pauli X, Y, Z flips; the Hadamard (H); the phase gate…
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Capability B.3: Below-Threshold Operation & Scaling
“Below-threshold operation” refers to running a quantum processor at error rates below the critical threshold of a quantum error-correcting code. In simple terms, there is a tipping point in error rates: if each quantum gate and qubit has an error probability lower than this threshold, adding more qubits and more…
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Capability B.2: Syndrome Extraction (Error Syndrome Measurement)
Quantum syndrome extraction - also called error syndrome measurement - is the process of measuring collective properties of qubits to detect errors without destroying the encoded quantum information. It is essentially the sensor mechanism of a quantum error-correcting code, analogous to measuring parity checks in a classical error-correcting code. In…
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Capability B.1: Quantum Error Correction (QEC)
Quantum Error Correction (QEC) is the first and arguably most critical capability in the roadmap toward a cryptographically relevant quantum computer (CRQC). Without QEC, a large-scale quantum computer cannot reliably perform the billions of operations needed to break modern encryption - no matter how many qubits we build. In essence,…
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Shor’s Algorithm: A Quantum Threat to Modern Cryptography
Shor’s Algorithm is more than just a theoretical curiosity – it’s a wake-up call for the security community. By understanding its principles and implications, we can appreciate why the cryptographic landscape must evolve. The goal of this guide is to equip you with that understanding, without delving into complex mathematics,…
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Grover’s Algorithm and Its Impact on Cybersecurity
Grover’s algorithm was one of the first demonstrations of quantum advantage on a general problem. It highlighted how quantum phenomena like superposition and interference can be harnessed to outperform classical brute force search. Grover’s is often described as looking for “a needle in a haystack” using quantum mechanics.
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Quantum Computing Hype and Fear: Same Song, New Verse
Another year, another wave of "quantum computers are about to crack all our encryption" fear-mongering. It’s 2012, and I’m getting déjà vu reading headlines proclaiming the imminent doom of RSA and other cryptography. I've been writing about this for at least 10 years. Ever since Peter Shor unveiled an algorithm…
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Are Quantum Computers a Real Threat?
Our conclusion is that quantum computers are not an imminent threat to cybersecurity. They are a fascinating technology and potential threat in the long term, but certainly not something that keeps me awake at night today. For our clients such as governments and critical infrastructure operators, the prudent advice is…
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Quantum Snake Oil
Don’t get me wrong - as a techno-geek at heart, I love the science of quantum computing. One day, it will upend cryptography as we know it. We’ll have to transition to new algorithms. That day will come - but it’s not here yet. It’s not even peeking over the…
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