Quantum Computing

PostQuantum.com by Marin Ivezic – Quantum Computing, Quantum Technologies, Post-Quantum

  • Quantum Error Correction QEC

    Quantum Errors and Quantum Error Correction (QEC) Methods

    Quantum error correction (QEC) is therefore critical for enabling large-scale or fault-tolerant quantum computing. Fault tolerance means a quantum computer can continue to operate correctly even when individual operations or qubits error out. Unlike classical error correction – which can simply duplicate bits and use majority vote – quantum error…

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  • Neven's Law Quantum Computing

    Neven’s Law: The Doubly Exponential Surge of Quantum Computing

    In 2019, Google’s Quantum AI director Hartmut Neven noticed something remarkable: within a matter of months, the computing muscle of Google’s best quantum processors leapt so quickly that classical machines struggled to keep up. This observation gave birth to “Neven’s Law,” a proposed rule of thumb that quantum computing power…

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  • Toffoli Gate Quantum

    The Toffoli Gate: The Unsung Workhorse in Quantum Codebreaking

    Understanding the Toffoli gate’s role isn’t just an academic exercise – it has real implications for when and how quantum computers might break our cryptography. Each Toffoli gate isn’t a single physical operation on today’s hardware; it has to be decomposed into the basic operations a quantum machine can do…

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  • Wave Function Collapse

    Wave Function Collapse: When Quantum Possibilities Become Reality

    Wave function collapse is the idea that a quantum system, described by a wave function embodying several possible states at once, suddenly reduces to a single state when observed. In simple terms, before you measure it, a quantum object can be in a superposition of many possibilities; when you measure…

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  • Cat Qubit

    Cat Qubits 101

    Bosonic “cat qubits” are quantum bits encoded in the states of bosonic oscillators (e.g. modes of a microwave cavity) that resemble Schrödinger’s famous alive/dead cat superposition. Instead of relying on a single two-level quantum element, a cat qubit stores information in two coherent states of a harmonic oscillator and their…

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  • Quantum Entanglement

    Quantum Entanglement: The “Spooky” Glue Uniting Qubits and Beyond

    From enabling quantum supercomputers to securing communications and teleporting quantum states, entanglement is the thread weaving through all of quantum technology. What once struck Einstein as a paradox is today routinely observed and harnessed in labs – the “spooky action” has become a practical tool. We have learned that entanglement…

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  • Transmon Qubits Quantum Computing

    Transmon Qubits 101

    Transmon qubits are a type of superconducting qubit designed to mitigate charge noise by shunting a Josephson junction with a large capacitor. In other words, a transmon is a superconducting charge qubit that has reduced sensitivity to charge fluctuations​. The device consists of a Josephson junction (a nonlinear superconducting element)…

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  • Glossary Quantum Computing Cybersecurity

    Glossary of Quantum Computing Terms

    Glossary of Quantum Computing, Quantum Networks, Quantum Mechanics, and Quantum Physics Terms for Cybersecurity Professionals.

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  • D-Wave Dilution Refrigerator Quantum Annealer

    Adiabatic Quantum Computing (AQC) and Impact on Cyber

    Adiabatic Quantum Computing (AQC), and its variant Quantum Annealing, are another model for quantum computation. It's a specialized subset of quantum computing focused on solving optimization problems by finding the minimum (or maximum) of a given function over a set of possible solutions. For problems that can be presented as…

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  • Quantum Mechanics Quantum Computers

    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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  • CNOT Gate 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…

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  • Quantum Random Circuit Sampling (RCS)

    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…

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  • Schrödinger Wave Equation

    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…

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  • Quantum Computing Introduction

    What’s the Deal with Quantum Computing: Simple Introduction

    Quantum computing holds the potential to revolutionize fields where classical computers struggle, particularly in areas involving complex quantum systems, large-scale optimization, and cryptography. The power of quantum computing lies in its ability to leverage the principles of quantum mechanics—superposition and entanglement—to perform certain types of calculations much more efficiently than…

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  • Quantum Parallelism

    Quantum Parallelism in Quantum Computing: Demystifying the “All-at-Once” Myth

    Quantum parallelism is often described in almost mystical terms – exponential computations happening in parallel in the multiverse! – but as we’ve explored, it boils down to the concrete physics of superposition and interference. A quantum computer superposes many states and processes them together, leveraging the wave-like nature of quantum…

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