The Vacuum Chamber: Why Atom Qubits Need Space Emptier Than Orbit
Ask most people what a quantum computer looks like and they picture a golden chandelier hanging inside a refrigerator. That image belongs to the super...
The QRAM Bottleneck: The Memory a Quantum Computer Doesn't Have Yet
Read a paper on a quantum algorithm for searching a database, recommending products, or running machine learning on a big dataset, and somewhere in th...
The Atom-Array Upstarts: How QuEra and Pasqal Bet on Neutral Atoms
Ask most people to picture a quantum computer and they imagine a gold chandelier hanging inside a refrigerator, or a chip cooled to a whisker above ab...
The Starling Plan: IBM's Roadmap to a Fault-Tolerant Machine
Most quantum computing roadmaps are marketing dressed as engineering. They show a curve climbing toward a million qubits and leave the awkward middle...
The Portfolio Problem: What Wall Street Wants From a Quantum Computer
Long before a quantum computer could do anything a laptop couldn't, the biggest banks had already signed up for access. JPMorgan, Goldman Sachs, HSBC...
The Crosstalk Curse: When Poking One Qubit Rattles Its Neighbors
A quantum processor is a crowded neighborhood. To perform useful computation, qubits need to sit close enough to interact, exchanging the entanglement...
The Frequency Collision: When Two Qubits Land Too Close
Build a superconducting quantum processor out of fixed-frequency transmons and you inherit a problem that has nothing to do with quantum mechanics and...
The Decoder's Deadline: The Classical Chip Racing to Outrun Qubit Errors
Most of the attention in quantum computing goes to the qubits: the trapped ions, the superconducting loops, the neutral atoms held in laser tweezers....
The Noise Eraser: Cleaning Quantum Results Without Fixing the Qubits
There are two ways to deal with a quantum computer's mistakes. You can fix them, or you can subtract them after the fact. Fixing them means error corr...
The Lattice Surgery: How Two Protected Qubits Shake Hands
Protecting a qubit is only half the job. Spread one logical qubit across a checkerboard of hundreds of physical qubits, wrap it in the error-correctin...
The Mid-Circuit Measurement: Reading a Qubit Without Ending the Job
For most of quantum computing's short history, measurement was a full stop. You loaded your circuit, let the qubits evolve, and only at the very end d...
The Utility Era: When a Noisy Quantum Computer Earned Its Keep
For years the story of quantum computing had two chapters. In the first, machines were toys: a handful of qubits solving problems any laptop could cra...
The Transpiler: How a Quantum Program Gets Squeezed Onto Real Qubits
Write a quantum program and you get to imagine a perfect machine. Any qubit can talk to any other. Your gates come in whatever flavor you like. Nothin...
The Clock Speed Divide: Why Some Qubits Run a Thousand Times Faster
Ask two engineers to name the most important number in a quantum computer and you will get two answers. One will say coherence time, the other fidelit...
The Reset Button: How a Quantum Computer Clears a Qubit
Before a quantum computer can do anything clever, it has to do something boring: put every qubit into a known starting state. Almost always that state...
The Shot Count: Why a Quantum Computer Runs the Same Job a Thousand Times
Ask a classical computer to add two numbers and it hands you the result. Ask a quantum computer to solve a problem and it hands you a coin flip. Run t...
The Optical Tweezer: How a Laser Grabs One Atom to Make a Qubit
Most descriptions of a neutral-atom quantum computer start with the qubits themselves, single rubidium or cesium atoms floating in a vacuum. But befor...
The Leakage Ladder: When a Qubit Climbs Out of Its Two States
A qubit is a fiction the hardware agrees to maintain. Physicists talk about two states, a crisp 0 and 1, but almost every real qubit is carved out of...
The Atom Menu: Why Trapped-Ion Makers Argue Over Which Element to Use
Before a trapped-ion quantum computer can hold a single qubit, someone has to pick which atom to trap. It sounds like a footnote, but it is one of the...
The Color Code: The Triangular Lattice That Does More Gates for Free
When people talk about protecting qubits, they almost always mean the surface code, the checkerboard arrangement that has become the default plan for...
The Noise Rewind: How a Quantum Computer Fakes a Cleaner Answer
There are two ways to deal with the errors that plague a quantum computer. One is to fix them outright, spreading a single unit of information across...