Why a Qubit ≠ Faster Bit

Example: Adding Two Numbers

Task: Calculate 1,234 + 5,678

Your laptop:

• Time: ~0.0000001 seconds
• Answer: 6,912
• Correct: ✅ Always

IBM's quantum computer:

• Time: ~5 seconds (plus queue wait)
• Answer: 6,912... maybe 6,911... or 6,913... 🤷
• Correct: ❌ Only about 95% of the time (due to noise)

For simple arithmetic, your laptop wins. Every time.

Problems where you need to explore MANY possibilities simultaneously.

Problem: You lost your keys somewhere in your house (100 rooms).

Classical approach:

• Check room 1... not here
• Check room 2... not here
• Check room 3... not here
• ...
• Average: Check 50 rooms before you find them

Quantum approach (conceptually):

• Create a superposition of "checking all 100 rooms at once"
• Use quantum interference to amplify the correct answer
• Average: Check only ~10 rooms (Grover's algorithm)

Note: This is a conceptual analogy. Real quantum search is more complex, but the principle holds.

Problem: Try all possible 8-character passwords (218 trillion combinations)

Classical computer:

• Try: "aaaaaaaa" ❌
• Try: "aaaaaaab" ❌
• Try: "aaaaaaac" ❌
• ...
• Time: Years (on average)

Quantum computer (with Grover's algorithm):

• Test all passwords "simultaneously" via superposition
• Use interference to find the correct one
• Time: Minutes to hours (quadratic speedup)

Task Type	Classical Computer	Quantum Computer
Simple Arithmetic	✅ Excellent	❌ Terrible
Sorting Data	✅ Excellent	❌ Worse
Playing Videos	✅ Excellent	❌ Impossible
Searching Unsorted Database	⚠️ Slow (N steps)	✅ Faster (√N steps)
Factoring Large Numbers	❌ Essentially impossible	✅ Feasible (Shor's algorithm)
Simulating Molecules	❌ Exponentially hard	✅ Natural fit
Optimization Problems	⚠️ Slow for complex cases	✅ Potentially much faster

Think of a maze:

• Classical: Try one path at a time. If wrong, backtrack and try another.
• Quantum: Superposition lets you explore ALL paths at once, then collapse to the correct answer.

Quantum algorithms are designed so that:

• Wrong answers: Cancel out (destructive interference)
• Right answers: Reinforce (constructive interference)

This is why quantum computers can find needles in haystacks faster than classical ones.

Entangled qubits can represent correlations that would require exponentially more classical bits.

Example:

• 300 entangled qubits can represent more states than there are atoms in the universe
• Classical computer would need 2³⁰⁰ bits to track the same information

Classical Computer = Single Worker

Imagine you need to find a specific book in a library with 1,000,000 books. A single worker checks one book at a time.

Parallel Classical Computer = Many Workers

You hire 1,000 workers. Each checks 1,000 books. Much faster, but you need 1,000 workers (expensive and physical).

Quantum Computer = Supernatural Detective

Instead of physically checking books, the quantum detective uses a "magic spell" (superposition) that lets them simultaneously sense all books, then uses interference to narrow down to the right one much faster than checking linearly—but the spell ONLY works for specific types of searches.

If you ask them to just "add 2+2," they're confused and slow. They're built for a different kind of task.

Classical + Quantum = Hybrid Systems

• Your laptop handles normal computing (UI, data processing, etc.)
• When you hit a quantum-suitable problem (optimization, simulation, search), send it to a quantum processor
• Quantum processor returns the answer
• Laptop continues with classical tasks

Quantum computers don't make bits faster.

They use superposition and interference to solve specific types of problems in ways that classical computers fundamentally cannot match—but only for those specific problems.

For everything else? Your laptop wins.