Let’s explore the physical process of creating a qubit. We will focus on IBM’s superconducting qubits since they’re a relevant example that you can interact with for free.
What’s a Qubit?
A qubit is the basic building block of a quantum computer, like a bit (0 or 1) in a classical computer. But unlike a regular bit, a qubit can be 0, 1, or in a state of superposition. To accomplish this, we need a physical system that can behave in a quantum manner.
Here is how IBM does it with superconducting qubits:
Step 1: Pick the Right Material
Superconductors: IBM uses tiny circuits usually made from materials like niobium or aluminum. These materials become "superconducting" when cooled to super-low temperatures (like -459°F, or close to absolute zero). When they are superconducting, electricity flows through them with zero resistance, which lets quantum effects occur with minimal noise.
Why This Matters: Normal electrical resistance would interfere with the quantum states we need for a qubit. Superconductivity aids in keeping everything stable.
Step 2: Build a Small Circuit
Josephson Junctions: The heart of IBM’s qubit is a tiny device called a Josephson junction. It’s made by combining a super-thin layer of insulating material (like aluminum oxide) between two superconducting pieces. This junction acts like a "quantum switch" that can control how energy flows.
Imagine a tiny dam in a river. The dam can let water (energy in this case) flow in a controlled way, and in the quantum world, this control allows us to create two distinct states: 0 and 1.
Step 3: Cool It Down
Cryogenic Fridge: The qubit is placed inside a special refrigerator called a dilution refrigerator. This cools the circuit to about 15 millikelvin (that is thousandths of a degree above absolute zero).
The Purpose of This: At room temperature, atoms move around too much. This interferes with the quantum state. Cooling it down helps to keep everything more stationary. This allows the qubit to maintain its quantum state.
Step 4: Turn It Into a Qubit
Energy Levels: The Josephson junction creates two specific energy levels in the circuit, which are labelled as 0 and 1.
Microwave Pulses: Next we zap the qubit with small microwave pulses. These pulses nudge the qubit into superposition or entangle it with other qubits.
Step 5: Keep It Stable
Shielding: The qubit is super reactive to outside noise. To combat this, it is kept in a shielded box to block out as much of this noise as possible.
Coherence Time: This is how long the qubit can hold its quantum state before it loses coherence. IBM and other quantum computer developers work hard to make this time as long as possible, because the longer this lasts, the more quantum calculations we can do.
Why This is Important for Quantum Computing:
This physical process lets IBM build qubits that can team up to solve problems way faster than regular computers for certain tasks. The difficulty is getting these fragile quantum states to work together reliably, which is why the cooling, shielding, and precise control are so important.
Top comments (0)