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Aquila (analog) has been live on Amazon Braket since 2022.
Gemini (digital) is installed in Japan.
Libra (fault-tolerant) is coming to Amazon Braket in 2028.
This architecture combines the elegance of nature’s most perfect qubits with the flexibility of programmable optical control.
Large-scale, defect-free arrays can be shaped on demand, connected in any pattern, and extended without sacrificing quality. These traits make neutral-atom systems uniquely suited to deliver scientific breakthroughs today while scaling toward the powerful, error-corrected machines that will redefine computing tomorrow.
Performing computations with neutral atoms involves realizing, controlling, manipulating, and measuring neutral atom qubits. Let's dive into some of the details.
Nature's perfect qubits
High-quality multi-qubit gates
Field programmable qubit arrays
Highly scalable architecture
Hybrid operation modes
Post-classical compute power
Atoms are nature's perfect qubits, all identical to one another. They are simultaneously capable of storing and processing quantum information, without significant cryogenic requirements. This gives an edge over manufactured qubits that can suffer from imperfections.
Our qubits are made of neutral atoms
Atoms consist of a nucleus and their electron cloud. At QuEra, we use Rubidium atoms. When the positive and negative charges of an atom balance each other, the atom is said to be neutral, just like most atoms are found in nature. By shining a laser at the atom, we can increase the energy of the atom, and excite it. Each atom has a wide range of potential excited states, each at different energy levels. This offers a great platform for storing and processing quantum information. Any choice of two such levels can be named ‘0’ and ‘1’ to form a qubit.
Controlled by lasers
We use lasers, acting as optical tweezers, to trap individual atoms in place. The lasers suppress atomic movement, effectively cooling the atoms down to nearly absolute zero temperature. At these temperatures, the individual discrete energy levels of the atoms can be resolved and manipulated, some of them leading to huge coherence times exceeding one second.
Rydberg atoms interact on-demand. When atoms are not excited, they are resilient to errors regardless of the total number of qubits in the system. This significantly increases the computational power of our machines.
Perform computations by puffing-up atoms
When atoms are excited to high-energy states, called Rydberg states, their electron clouds puff up to a relatively enormous scale, about a thousand times their original size. In this Rydberg state, different atoms can interact over long distances, enabling quantum information to be transferred between them. This enables entanglement, one of the key ingredients for quantum information manipulation.
The interaction mechanism between Rydberg atoms is known as the 'van der Waals' interaction, which originates from the strong dipole moments of the expanded atoms. This interaction diminishes with the sixth power of the interatomic distance, implying that atoms interact intensely only when they are in close proximity. In fact, this interaction can become so powerful that it can induce the 'Rydberg blockade' effect, whereby no two adjacent atoms can be excited simultaneously. This mechanism enables the implementation of conditional quantum logic and two-qubit gates.
Long-range Rydberg interactions can be used to reduce the gate-decomposition overhead of multi-qubit gates. This minimizes errors and increases processing speed.Related research: High-fidelity gates and connectivity (arXiv preprint)
Entangling multiple qubits
Remarkably, the size of Rydberg atoms can encompass several nearby qubits, allowing for mutual interaction. Unlike most quantum computers that can only implement native 1-qubit and 2-qubit gates, the Rydberg blockade mechanism facilitates the development of native multi-qubit gates.
Gates such as the Toffoli gate (refer to the image on the left) hold significant importance in numerous quantum algorithms. By natively encoding these multi-qubit gates, the circuit depth of the algorithm can be substantially reduced, thereby significantly mitigating errors. A prime example of this is the constant-depth implementation of Shor’s algorithm.