All Quantum Computing Posts
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Quantum Computing
Routing Quantum Information: SWAP, iSWAP, and Moving Qubit States
Quantum computers face a unique challenge in moving quantum information between qubits. Unlike classical bits that can be shuttled freely along wires, qubits cannot be arbitrarily copied or moved due to the no-cloning theorem. To route a qubit’s state from one location to another, one must use quantum operations that effectively reposition the state without making a separate copy. This is especially critical in architectures…
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Quantum Computing
Surface Code Quantum Error Correction
Quantum error correction (QEC) is indispensable for building large-scale fault-tolerant quantum computers. Even today’s best qubits suffer error rates that would quickly corrupt any long calculation if left uncorrected. The principle of QEC is to encode a single logical qubit into multiple physical qubits such that errors can be detected and fixed without measuring the actual quantum data. Among many QEC codes, the surface code…
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Quantum Computing
Quantum Supremacy vs. Quantum Advantage
In the ever-accelerating world of quantum computing, two terms have emerged as the darlings of headlines and conference keynotes: quantum supremacy and quantum advantage. If you've followed the news, you might think they're interchangeable buzzwords celebrating the dawn of a new computing era. But dig a little deeper, and you'll uncover a subtle yet spirited debate among the field's top minds - one that's as…
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Quantum Computing
Early History of Quantum Computing
Since the early 2000s, the field of quantum computing has seen significant advancements, both in technological development and in commercialization efforts. The experimental demonstration of Shor's algorithm in 2001 proved to be one of the key catalyzing events, spurring increased interest and investment from both the public and private sectors.
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Quantum Computing
The Controlled-NOT (CNOT) Gate in Quantum Computing
The CNOT gate is to quantum circuits what the XOR gate is to classical circuits: a basic building block for complex operations. By learning how the CNOT gate works and why it matters, cybersecurity experts can better appreciate how quantum computers process information, how they might break cryptography, and how they enable new secure protocols. This article provides an accessible yet rigorous overview of the…
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Quantum Computing
Random Circuit Sampling (RCS) Benchmark
At its core, Random Circuit Sampling (RCS) is a way to test how well a quantum computer can generate the output of a complex quantum circuit. Compare the results to what an ideal quantum computer should produce. If the quantum computer’s output closely matches the theoretical expectations, it demonstrates that the system is performing quantum operations correctly.
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Quantum Computing
Schrödinger’s Wave Equation
Schrödinger’s equation is essentially the master instruction set for quantum systems – the quantum-world analogue of Newton’s famous F=ma in classical physics. In short, Schrödinger’s equation is to quantum mechanics what Newton’s second law is to classical mechanics: a fundamental law of motion describing how a physical system will change over time. It was formulated in 1925–26 by Erwin Schrödinger, who built on the idea…
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Quantum Computing
Beyond “Many Paths at Once”: The True Power of Quantum Computers
Quantum computers are often described with a mind-bending metaphor: they explore multiple paths simultaneously to find an answer. You might have heard people excitedly say that a quantum computer can "try all solutions at once" thanks to quantum magic. This popular explanation isn’t exactly wrong - it’s a handy metaphor to get started - but it doesn’t tell the full story. In reality, quantum computers…
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