Single-site Rydberg addressing in 3D atomic arrays for quantum computing with neutral atoms

Abstract

Neutral atom arrays are promising for large-scale quantum computing especially because it is possible to prepare large-scale qubit arrays. An unsolved issue is how to selectively excite one qubit deep in a 3D atomic array to Rydberg states. In this work, we show two methods for this purpose. The first method relies on a well-known result: in a dipole transition between two quantum states driven by two off-resonant fields of equal strength but opposite detunings ±∆, the transition is characterized by two counter-rotating Rabi frequencies Ωe ±i∆t [or ±Ωe ±i∆t if the two fields have a πphase difference]. This pair of detuned fields lead to a time-dependent Rabi frequency 2Ω cos(∆t) [or 2iΩ sin(∆t)], so that a full transition between the two levels is recovered. We show that when the two detuned fields are sent in different directions, one atom in a 3D optical lattice can be selectively addressed for Rydberg excitation, and when its state is restored, the state of any nontarget atoms irradiated in the light path is also restored. Moreover, we find that the Rydberg excitation by this method can significantly suppress the fundamental blockade error of a Rydberg gate, paving the way for a high-fidelity entangling gate with commonly used quasi-rectangular pulse that is easily obtained by pulse pickers. Along the way, we find a second method for single-site Rydberg addressing in 3D, where a selected target atom can be excited to Rydberg state while preserving the state of any nontarget atom due to a spin echo sequence. The capability to selectively address a target atom in 3D atomic arrays for Rydberg excitation makes it possible to design large-scale neutral-atom information processor based on Rydberg blockade.

Geyser

“…An attractive aspect of neutral atom quantum computing, compared to its competing technologies is that its qubits (atoms) can be arranged in any desired fashion. Prior engineering works have demonstrated the arrangement of atom in a variety of shapes (e.g., in the shape of Eiffel tower [5,37,40]). For practical feasibility and efficiency, we would like for the atoms to be arranged in a grid with some pattern-based distance properties to ensure Rydberg interactions.…”

“…the most promising technologies -each offering their own unique advantages over other competing technologies [3,8,21,37]. We anticipate that multiple technologies will be in production to serve different mission needs and local-technological expertise.…”

Rydberg quantum computation with nuclear spins in two-electron neutral atoms

“…In the Rydberg blockade gate [8,10], the blockade error is estimated by averaging gate errors with interactions varying around the desired V . This is because the blockade error can accidentally vanish [58] for a certain V that depends on the impossible condition of absolutely static atoms. Thus, we use Eq.…”

Transition Slow-Down by Rydberg Interaction of Neutral Atoms and a Fast Controlled-not Quantum Gate

“…A π phase change (requiring a time ǫ) is inserted between the pulses sent to the target qubit so as to induce spin echo, where ǫ can be around 10 ns [43]. The spin echo suppresses the state swap of the target qubit if the control qubit is initialized in |0 [73,74]; but when the control qubit is initialized in |1 , it is pumped to |r which results in TSD in the target qubit, i.e., the transition |0 ⇋ |r ⇋ |1 in the target qubit, which can occur with a pulse duration √ 2π/Ω t if no TSD is used [75], will be slowed down by a fold of √ 3. The mechanism is understood in two steps.…”