What Is a Field-Programmable Qubit Array?

A field-programmable qubit array (FPQA) is a neutral-atom processor in which software can rearrange the physical positions of the qubits, and so change which qubits interact, even in the middle of a computation. The name borrows from the field-programmable gate array (FPGA), a chip whose wiring the user sets after manufacture.

In a fixed-wiring processor, connectivity is a property of the chip. In an FPQA, atoms held in optical tweezers are moved physically, so connectivity becomes reconfigurable by the program, within the processor's motion and spacing constraints. The qubits are identical neutral atoms; what changes is where they sit.

Bluvstein and colleagues demonstrated in 2022 that atoms can be transported across an array while their entanglement is preserved. Their follow-up, published online in December 2023 and in Nature volume 626 in 2024, ran circuits on logical qubits using reconfigurable atom arrays.

How an FPQA Moves Atoms and Entangles Them

Two kinds of traps work together. A static grid of tweezers, often produced with a spatial light modulator, holds atoms in place. A second set of mobile tweezers, steered by acousto-optic deflectors, picks atoms up, carries them and sets them down at new sites. This is qubit shuttling. A simpler form, atom rearrangement before a run, was used to assemble defect-free arrays by Endres et al. and Barredo et al. in 2016.

Entangling gates rely on the Rydberg blockade. An atom excited to a Rydberg state interacts strongly with its neighbors through a van der Waals potential that falls off steeply with distance:

Within the blockade radius, typically a few micrometers, simultaneous excitation of two atoms is strongly suppressed, which can be used to implement a controlled-phase two-qubit gate. At larger separations the interaction is much weaker. Moving atoms together or apart therefore changes the interaction strength, making it large enough for gates or small enough to neglect.

What Programmable Connectivity Buys

This programmable connectivity matters in three ways:

• Code choice: many high-rate codes with non-local checks, such as qLDPC codes, need connections that are costly on a fixed two-dimensional grid. Moving atoms can supply them in principle.
• Zoned layouts: atoms can idle in a storage region and move to a separate entangling region, the idea behind a zoned architecture.
• Per-circuit layouts: a quantum compiler can choose the atom layout for each circuit instead of bending the circuit to fit one layout.

In the 2023 logical-processor work, reconfigurable atom arrays were used to apply gates between encoded blocks of qubits.

Limits and Common Misreadings

"Field-programmable" does not mean unconstrained.

• Movement takes time. Gates last about a microsecond or less, while moves typically take tens to hundreds of microseconds. That time counts against the coherence budget.
• Not all-to-all for free. Pairs can be brought together through legal move schedules, but the cost depends on distance and on what else is moving.
• Shared control. Atoms in the same row or column of the mobile trap grid move together, and the row and column order must be preserved, so compilers must find legal move schedules.
• Atom loss and heating during transport must be managed.

Programmable hardware should also not be confused with a mature, large-scale, fault-tolerant quantum computer. As QuEra's Mythbuster post argues, quantum computing is not ready for large-scale production, but it is ready for serious, structured engagement.

Where This Fits at QuEra

QuEra builds neutral-atom computers, so tweezer arrays are its native medium. Aquila, an analog system on Amazon Braket since 2022, lets users define atom positions in two dimensions for each program, and those positions set the interactions in the Hamiltonian being simulated. It is also offered through Kipu Quantum's PlanQK platform. Positions on Aquila are set before each run.

Gemini is a gate-based system, on premises since 2025. FPQA names a hardware model used in the research literature and in descriptions of neutral-atom systems, not a standalone QuEra product.

FAQ

Is an FPQA a product?

Not by itself. FPQA is a hardware-model term: neutral atoms in tweezers whose positions can be changed by software. Different systems implement parts of that model to different degrees.

How is an FPQA different from a fixed atom array?

In a fixed array, atoms stay at the sites where they were loaded, so the interaction pattern is set before the run. In an FPQA, atoms can also be moved during the run, changing which pairs can interact.

Does moving atoms destroy entanglement?

Not necessarily. Bluvstein et al. showed in 2022 that atoms can be transported while their entanglement is preserved. Moves still add time and risk atom loss, so they must be budgeted.

Key Takeaways

• An FPQA lets the program reconfigure connectivity within hardware constraints: atoms in optical tweezers are moved, and Rydberg interactions switch on at short range.
• Programmable connectivity supports codes with non-local checks and zoned layouts.
• Movement costs time and is constrained by shared control, so an FPQA is not free all-to-all connectivity.
• FPQA is a hardware-model term used in the literature and in neutral-atom system descriptions, not a standalone product name.