🚀 𝟯𝟬 𝗗𝗮𝘆𝘀 • 𝟯𝟬 𝗖𝗼𝗻𝗰𝗲𝗽𝘁𝘀 𝗼𝗳 𝗤𝘂𝗮𝗻𝘁𝘂𝗺 𝗖𝗼𝗺𝗽𝘂𝘁𝗶𝗻𝗴 | 𝗗𝗮𝘆 𝟭𝟭

Hi everyone !

“Classical computers process bits. Quantum computers transform quantum states.”

In the previous post, we learned that a qubit is described by probability amplitudes, not just probabilities. These amplitudes behave like waves and determine the likelihood of measuring 0 or 1.

But this leads to an important question…

🤔 How does a quantum computer change these amplitudes to perform computation?

The answer is Quantum Gates.

𝗪𝗵𝗮𝘁 𝗮𝗿𝗲 𝗤𝘂𝗮𝗻𝘁𝘂𝗺 𝗚𝗮𝘁𝗲𝘀?

In a classical computer, logic gates like AND, OR, and NOT manipulate bits.

A quantum computer also uses gates — but instead of changing bits, they transform the quantum state of qubits.

Rather than simply flipping 0 to 1, quantum gates modify a qubit’s probability amplitudes and phase, allowing it to evolve according to the laws of quantum mechanics.

Think of them as the instructions that guide how a qubit changes over time.

𝗧𝗵𝗲 𝗛𝗮𝗱𝗮𝗺𝗮𝗿𝗱 (𝗛) 𝗚𝗮𝘁𝗲

Imagine a qubit starts in the state:

|0⟩

Measuring it now always gives 0.

Now apply a Hadamard (H) Gate.

The state becomes:

(|0⟩ + |1⟩) / √2

The H gate doesn’t tell the qubit to become 1.

Instead, it transforms the quantum state so that measuring the qubit gives:

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• 50% → |0⟩
• 50% → |1⟩

It creates superposition, enabling the qubit to explore multiple possibilities simultaneously.

𝗧𝗵𝗲 𝗭 𝗚𝗮𝘁𝗲: 𝗖𝗵𝗮𝗻𝗴𝗶𝗻𝗴 𝗣𝗵𝗮𝘀𝗲

Now apply a Z Gate.

The state changes to:

(|0⟩ − |1⟩) / √2

Interestingly, the measurement probabilities remain 50% and 50%.

So what changed?

The phase.

Although invisible during a single measurement, phase determines how qubits interfere with each other after more quantum gates are applied. This interference strengthens some outcomes while weakening others.

𝗪𝗵𝘆 𝗔𝗿𝗲 𝗤𝘂𝗮𝗻𝘁𝘂𝗺 𝗚𝗮𝘁𝗲𝘀 𝗦𝗼 𝗜𝗺𝗽𝗼𝗿𝘁𝗮𝗻𝘁?

A quantum computer doesn’t solve problems by checking every answer one by one.

Instead, it applies carefully designed quantum gates that continuously reshape amplitudes and phases.

Through quantum interference, the probability of correct answers increases while incorrect ones become less likely.

Only after all these transformations are complete does the computer perform a measurement.

This is the foundation of powerful algorithms like Grover’s Search and Shor’s Algorithm.

𝗧𝗵𝗼𝘂𝗴𝗵𝘁 𝗼𝗳 𝘁𝗵𝗲 𝗗𝗮𝘆

“Quantum gates don’t tell a qubit what answer to give — they shape the wave that makes the right answer most likely.”

𝗡𝗲𝘅𝘁 𝗶𝗻 𝘁𝗵𝗲 𝗦𝗲𝗿𝗶𝗲𝘀

𝗗𝗮𝘆 𝟭𝟮 • 𝗤𝘂𝗮𝗻𝘁𝘂𝗺 𝗖𝗶𝗿𝗰𝘂𝗶𝘁𝘀: 𝗛𝗼𝘄 𝗤𝘂𝗮𝗻𝘁𝘂𝗺 𝗚𝗮𝘁𝗲𝘀 𝗪𝗼𝗿𝗸 𝗧𝗼𝗴𝗲𝘁𝗵𝗲𝗿 𝘁𝗼 𝗦𝗼𝗹𝘃𝗲 𝗖𝗼𝗺𝗽𝗹𝗲𝘅 𝗣𝗿𝗼𝗯𝗹𝗲𝗺𝘀.