--- title: Quantum Computing, Seen Through the Eyes of an Old IT... description: A beginner-friendly walkthrough of quantum computing concepts using Python code and circuit diagrams. Covers Bell states (Phi+ correlated and Psi+... canonical: https://daily.dev/posts/quantum-computing-seen-through-the-eyes-of-an-old-it-guy-part-5--bq5bwmdk8 twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Quantum Computing, Seen Through the Eyes of an Old IT Guy (Part 5) | daily.dev og:description: A beginner-friendly walkthrough of quantum computing concepts using Python code and circuit diagrams. Covers Bell states (Phi+ correlated and Psi+... og:url: https://daily.dev/posts/quantum-computing-seen-through-the-eyes-of-an-old-it-guy-part-5--bq5bwmdk8 og:image: https://api.daily.dev/og/posts/bQ5bWmdK8.png og:image:alt: Quantum Computing, Seen Through the Eyes of an Old IT Guy (Part 5) og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Quantum Computing, Seen Through the Eyes of an Old IT Guy (Part 5) **[Medium](https://daily.dev/sources/medium_js)** · 6 min read · 0 upvotes · 0 comments ## Summary A beginner-friendly walkthrough of quantum computing concepts using Python code and circuit diagrams. Covers Bell states (Phi+ correlated and Psi+ anti-correlated entanglement) with line-by-line code explanations, then moves into syndrome measurement for phase error detection using ancilla qubits. The author, a non-programmer IT veteran, explains how H gates, CNOT gates, X gates, Z gates, and phase kickback work together, and how ancilla qubits allow error detection without collapsing the data qubit's state. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### How do you create a Bell state (entangled qubits) in Qiskit-style Python code? Prepare a QuantumCircuit with 2 qubits and 2 classical bits, apply a Hadamard gate to qubit 0 with h(0) to create superposition, then apply cx(0, 1) so qubit 0 controls a flip of qubit 1, entangling them. Measuring both with measure([0, 1], [0, 1]) yields (0,0) or (1,1) each roughly 50% of the time, since the qubits are correlated. _For hands-on Bell state and entanglement code walkthroughs, daily.dev surfaces quantum computing tutorials developers are learning from._ ### How do you detect a phase-flip error on a qubit without destroying its data using syndrome measurement? Use an ancilla qubit: put the data qubit in superposition with h(q_data), simulate a phase error with z(q_data), superpose the ancilla with h(q_ancilla), entangle them with cx(q_ancilla, q_data) so phase kickback transfers the error sign onto the ancilla, apply h(q_ancilla) again, then measure only the ancilla into a syndrome bit. A result of 1 indicates a phase error occurred; 0 means none, and the data qubit itself is never measured or destroyed. _Developers building intuition for quantum error correction can track syndrome measurement explainers like this on daily.dev._ ### What is the difference between the Phi+ and Psi+ Bell states? Phi+ is a Bell state where entangled qubits always measure the same value, either (0,0) or (1,1), each about 50% of the time, produced by applying h(0) then cx(0,1). Psi+ is anti-correlated: an added x(1) flip before the same h and cx sequence makes the qubits always differ, yielding (0,1) or (1,0) each about 50% of the time. The plus/minus naming reflects a phase sign difference among the four Bell states. _Anyone comparing entanglement patterns like Bell states can find similar quantum computing breakdowns via daily.dev._ ## Similar posts on daily.dev - [Quantum Computing Basics With Qiskit – Real Python](https://daily.dev/posts/quantum-computing-basics-with-qiskit-real-python-hcfrsih9v) · Real Python · 1 upvotes · 0 comments - [A Beginner’s Guide to Quantum Computing with Python](https://daily.dev/posts/a-beginner-s-guide-to-quantum-computing-with-python-unxycrdrl) · Towards Data Science · 0 upvotes · 0 comments - [How to Write Your First Quantum Circuit in Python: A Beginner's Step-by-Step Guide](https://daily.dev/posts/how-to-write-your-first-quantum-circuit-in-python-a-beginner-s-step-by-step-guide-vi7cii7qt) · freeCodeCamp · 2 upvotes · 0 comments --- Tags: [#python](https://daily.dev/tags/python), [#quantum-computing](https://daily.dev/tags/quantum-computing), [#qiskit](https://daily.dev/tags/qiskit) [View this post on daily.dev](https://daily.dev/posts/quantum-computing-seen-through-the-eyes-of-an-old-it-guy-part-5--bq5bwmdk8) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Quantum Computing, Seen Through the Eyes of an Old IT Guy (Part 5)","url":"https://daily.dev/posts/quantum-computing-seen-through-the-eyes-of-an-old-it-guy-part-5--bq5bwmdk8","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/quantum-computing-seen-through-the-eyes-of-an-old-it-guy-part-5--bq5bwmdk8"},"datePublished":"2026-07-17T16:01:43.921Z","dateModified":"2026-09-13T20:41:00.259Z","description":"A beginner-friendly walkthrough of quantum computing concepts using Python code and circuit diagrams. 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Measuring both with measure([0, 1], [0, 1]) yields (0,0) or (1,1) each roughly 50% of the time, since the qubits are correlated. For hands-on Bell state and entanglement code walkthroughs, daily.dev surfaces quantum computing tutorials developers are learning from."}},{"@type":"Question","name":"How do you detect a phase-flip error on a qubit without destroying its data using syndrome measurement?","acceptedAnswer":{"@type":"Answer","text":"Use an ancilla qubit: put the data qubit in superposition with h(q_data), simulate a phase error with z(q_data), superpose the ancilla with h(q_ancilla), entangle them with cx(q_ancilla, q_data) so phase kickback transfers the error sign onto the ancilla, apply h(q_ancilla) again, then measure only the ancilla into a syndrome bit. A result of 1 indicates a phase error occurred; 0 means none, and the data qubit itself is never measured or destroyed. 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