What is the largest number of qubits entangled so far?

In one line

The rule

Entanglement is a quantum phenomenon where two or more qubits (quantum bits) are linked so that the state of one instantly affects the state of the other, no matter how far apart they are.

There is no single formula for the 'largest entangled system', but the number is usually reported as the count of qubits in a single, verified entangled state.

Let's understand it simply

Imagine you and your friends are holding hands in a circle. If one person moves, everyone feels it. In quantum computers, qubits (quantum bits) can be linked together in a special way called entanglement. When qubits are entangled, changing one instantly affects the others, even if they are far apart—like magic strings connecting them.

Making many qubits hold hands (entangle) at the same time is very hard. The more qubits you add, the harder it is to keep them all connected without breaking the link.

How it works

1. Scientists use lasers, microwaves, or electric fields to control qubits (which can be atoms, ions, or tiny circuits).
2. They prepare each qubit in a special state, often called a superposition (a mix of 0 and 1 at the same time).
3. They use special operations (quantum gates) to link the qubits together, creating entanglement.
4. They check if the qubits are truly entangled using measurements and mathematical tests.
5. As more qubits are added, it gets harder to keep them entangled because of noise (unwanted changes from the environment).
6. The record is set when a team can show, with proof, that all qubits are entangled at once.

The story behind it

Quantum entanglement was first discussed by Albert Einstein, Boris Podolsky, and Nathan Rosen in 1935 (the EPR paradox). They thought it was strange and called it "spooky action at a distance." Later, experiments proved entanglement is real. In the 21st century, scientists started using entanglement in quantum computers. Each year, teams try to entangle more qubits to make more powerful quantum machines.

In 2021, IBM announced a 127-qubit quantum processor (Eagle), and in 2022, Chinese researchers entangled 60 photons. Other groups have entangled 20–50 trapped ions or superconducting qubits. The exact record depends on the type of qubit and how strict the test is.

Where you see it in real life

• Quantum computers: Entanglement lets them solve problems much faster than normal computers.
• Quantum teleportation: Sending information instantly using entangled qubits.
• Quantum cryptography: Making unbreakable codes for secure messages.
• Quantum sensors: Super-sensitive devices for measuring tiny changes in gravity or magnetic fields.
• Research labs: Scientists use entanglement to test the limits of physics.
• Quantum internet (future): Sending entangled information across cities or countries.

Why it matters

• Entanglement is the key to making quantum computers powerful.
• It can make communication super secure (no one can secretly listen in).
• It helps us understand the deepest rules of nature.
• Many future technologies (like quantum internet) depend on making and controlling large entangled states.

Worked example

Let’s look at a real record:

Given: IBM Eagle processor, 127 superconducting qubits
Step 1: Prepare all 127 qubits in a superposition
Step 2: Apply quantum gates to entangle them
Step 3: Measure the system to check for entanglement
Step 4: Confirm that all 127 qubits are entangled (using mathematical tests)
Step 5: Announce the result as a new record

Common mistakes

• Thinking all qubits in a quantum computer are always entangled. (Most are not; entanglement is hard to keep.)
• Believing the record is the same for all types of qubits. (Photons, ions, and circuits have different records.)
• Confusing 'number of qubits' with 'number of entangled qubits.' (A computer may have 1000 qubits, but only 50 are entangled at once.)
• Assuming entanglement means perfect control. (Noise and errors can break the link.)

Remember it

"Entanglement is like magic strings—more qubits, harder to keep them all tied together."