Building a 20-Qubit Quantum System Using Photons

hari@dasarpai.com (Dr. Hari Thapliyaal) — Mon, 24 Aug 2026 00:00:00 +0000

Building a 20-Qubit Quantum System Using Photons
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Quantum computing often becomes difficult to understand because we start directly with symbols such as:

|0>, |1>, superposition, entanglement, Hilbert space, and quantum gates.

A simpler approach is to start with the physical system — the actual hardware — and only then attach the math.

Let us assume that we want to build a 20-qubit quantum system using photons.

The central idea is:

One photon can be used as one qubit if we choose one two-state property of that photon to represent |0> and |1>.

For this article, we will use the polarization of a photon.

If you write software
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If you already think in bits, registers, and logic gates, here is the mapping this article uses:

Classical computing	Photonic qubits (this article)
One bit: `0` or `1`	One qubit: two basis states labeled `\|0>` and `\|1>`
20-bit register: one of 2^20 bit strings	20-qubit register: one joint state in a 2^20-dimensional vector space
AND / OR / NOT gates	Unitary transforms implemented with wave plates, beam splitters, and phase shifters
Read register → get 20 bits	Measure 20 qubits → get one 20-bit outcome per experimental run

The goal is not to memorize optics. It is to see where the symbols in a quantum circuit come from physically — so notation like |0>, |+>, tensor products, and entanglement map to hardware you could, in principle, build in a lab.

Throughout, |0> and |1> are Dirac ket labels (basis state names), not ASCII angle brackets around integers.

Linear Algebra on dasarpAI

Building a 20-Qubit Quantum System Using Photons

Building a 20-Qubit Quantum System Using Photons #

If you write software #

Building a 20-Qubit Quantum System Using Photons
#

If you write software
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