My First Qubit
The Quantum Turtle · Quantum Play Lab
My First Qubit
Two circles show one qubit. Move the sliders, press a gate, and see what changes.
Chance of 1. Halfway = 50%; the angle-to-chance relationship is curved.
Sets the difference between the clock hands
See the math
Both circles show one state:
|ψ⟩ = a|0⟩ + b|1⟩
Each coefficient shows its real and imaginary parts, even when zero. Both phases evolve during gates; global phase does not affect measurement. Values are rounded. θ = .
Start at |0⟩. Try a slider or gate!
Try this first
- Start at |0⟩. The blue circle is full.
- Press H. Both circles show a 50% chance.
- Press Z. The hands turn in opposite directions, but the chances stay the same.
- Press H again, then Measure. You will get 1.
Ready for the next step? Explore The Bloch Sphere →
What the board shows
Two circles show one qubit. Each circle's filled area shows the chance of measuring that result. Balance angle (θ) makes one circle grow as the other shrinks. The displayed chance of 1 is P(1) = sin²(θ/2), so equal turns of the angle knob do not produce equal changes in probability. Relative Phase (φ) sets the difference between the hands when you move the slider. Each hand shows the phase of its complex amplitude. Only the difference between the hands changes measurement behavior. When both hands rotate together, that is global phase, which does not affect measurement results. When a circle is empty, its clock hand has no direction. The phase setting stays saved until both circles have a size. Mathematically, relative phase is undefined when either amplitude is zero.
These sliders can show any pure state of one qubit. A mixed state needs a different model.
This browser toy is a first step toward a real wooden busy board. The real toy could use turning knobs and two small screens. It runs on your computer, not on quantum hardware.
From screen to real life
We're building a physical My First Qubit with real controls and two round displays. The first electronics prototype is underway.