Demonstration of a Neutral Atom Controlled-NOT Quantum Gate

Abstract

We present the first demonstration of a CNOT gate between two individually addressed neutral atoms. Our implementation of the CNOT uses Rydberg blockade interactions between neutral atoms held in optical traps separated by >8 microm. Using two different gate protocols we measure CNOT fidelities of F=0.73 and 0.72 based on truth table probabilities. The gate was used to generate Bell states with fidelity F=0.48+/-0.06. After correcting for atom loss we obtain an a posteriori entanglement fidelity of F=0.58.

Many-body physics with alkaline-earth Rydberg lattices

“…The strong interactions inhibit the excitation of neighbouring atoms to the Rydberg state in an effect known as the dipole blockade [1,2]. This effect has been elegantly demonstrated in experiments using two independently trapped atoms [3,4], where it has also been exploited to entangle qubits [5], and perform gate operations [6,7]. The utility of tunable Rydberg-Rydberg interactions is not limited to two atoms, and has lead to the theoretical development of a remarkably versatile toolbox for quantum information processing [8].…”

Chirped pulse excitation of two-atom Rydberg states

“…In this regime of a Rydberg blockade the strong interaction prevents excitation of a second atom if the first atom has been excited. The blockade has been experimentally demonstrated for two atoms in separate dipole traps [4], followed by realization of a CNOT gate [5] and entanglement [6]. A second approach to the controlled phase gate, discussed in [3], applies to smaller interaction strengths V int < ∼ Ω, for which the blockade cannot work.…”

Photon-photon gate via the interaction between two collective Rydberg excitations

“…One attractive approach involves converting the photons into atomic excitations in highly excited Rydberg states, which exhibit strong interactions. Rydberg state based quantum gates between individual atoms and between atomic ensembles have been proposed [6][7][8][9][10] and implemented [11][12][13]. There are two categories of gates, those relying on the interaction between two excited atoms [6,7], and those based on Rydberg blockade [7][8][9][10][11][12][13], where only one atom is excited at any given time.…”

“…Rydberg state based quantum gates between individual atoms and between atomic ensembles have been proposed [6][7][8][9][10] and implemented [11][12][13]. There are two categories of gates, those relying on the interaction between two excited atoms [6,7], and those based on Rydberg blockade [7][8][9][10][11][12][13], where only one atom is excited at any given time. There is a significant body of work studying the effects of mapping photons onto collective atomic Rydberg excitations [14][15][16][17][18][19][20].…”