Local Blockade of Rydberg Excitation in an Ultracold Gas

Tong, D.; Farooqi, S. M.; Stanojevic, Jovica; Krishnan, S. S.; Zhang, Y. P.; Côté, Robin; Eyler, E. E.; Gould, Phillip L.

doi:10.1103/physrevlett.93.063001

Cited by 570 publications

(562 citation statements)

References 15 publications

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“…The dominant term in the long-range electrostatic interaction series between two Rydberg atoms is the dipole-dipole interaction term [45]. This interaction is at the origin of diverse phenomena in cold Rydberg atom gases, such as resonant transitions of Rydberg-atom pairs [46,47], inelastic collisions [2], Penning ionization [48,49], Rydberg-excitation blockade [50][51][52] and the formation of Rydberg macrodimers [53][54][55]. It also plays an important role in the evolution of a cold Rydberg gas into a plasma [56][57][58].…”

Section: A Collision-induced Transitions Between Near-degenerate Levmentioning

confidence: 99%

Radiative and collisional processes in translationally cold samples of hydrogen Rydberg atoms studied in an electrostatic trap

Seiler¹,

Agner²,

Pillet³

et al. 2016

J. Phys. B: At. Mol. Opt. Phys.

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Supersonic beams of hydrogen atoms, prepared selectively in Rydberg-Stark states of principal quantum number n in the range between 25 and 35, have been deflected by 90 ○ , decelerated and loaded into off-axis electric traps at initial densities of ≈ 10 6 atoms/cm −3 and translational temperatures of 150 mK. The ability to confine the atoms spatially was exploited to study their decay by radiative and collisional processes. The evolution of the population of trapped atoms was measured for several milliseconds in dependence of the principal quantum number of the initially prepared states, the initial Rydberg-atom density in the trap, and the temperature of the environment of the trap, which could be varied between 7.5 K and 300 K using a cryorefrigerator. At room temperature, the population of trapped Rydberg atoms was found to decay faster than expected on the basis of their natural lifetimes, primarily because of absorption and emission stimulated by the thermal radiation field. At the lowest temperatures investigated experimentally, the decay was found to be multiexponential, with an initial rate scaling as n −4 and corresponding closely to the natural lifetimes of the initially prepared Rydberg-Stark states. The decay rate was found to continually decrease over time and to reach an almost n-independent rate of more than (1 ms) −1 after 3 ms. To analyze the experimentally observed decay of the populations of trapped atoms, numerical simulations were performed which included all radiative processes, i.e., spontaneous emission as well as absorption and emission stimulated by the thermal radiation. These simulations, however, systematically underestimated the population of trapped atoms observed after several milliseconds by almost two orders of magnitude, although they reliably predicted the decay rates of the remaining atoms in the trap. The calculations revealed that the atoms that remain in the trap for the longest times have larger absolute values of the magnetic quantum number m than the optically prepared RydbergStark states, and this observation led to the conclusion that a much more efficient mechanism than a purely radiative one must exist to induce transitions to Rydberg-Stark states of higher m values. While searching for such a mechanism, we discovered that resonant dipole-dipole collisions between Rydberg atoms in the trap represent an extremely efficient way of inducing transitions to states of higher m values. The efficiency of the mechanism is a consequence of the almost perfectly linear nature of the Stark effect at the moderate field strengths used to trap the atoms, which permits cascades of transitions between entire networks of near-degenerate Rydberg-atom-pair states. To include such cascades of resonant dipole-dipole transitions in the numerical simulations, we have generalized the two-state Förster-type collision model used to describe resonant collisions in ultracold Rydberg gases to a multi-state situation. It is only when considering the combined effects of collisional and radiative pr...

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Section: A Collision-induced Transitions Between Near-degenerate Levmentioning

confidence: 99%

Radiative and collisional processes in translationally cold samples of hydrogen Rydberg atoms studied in an electrostatic trap

Seiler¹,

Agner²,

Pillet³

et al. 2016

J. Phys. B: At. Mol. Opt. Phys.

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“…Here we demonstrate a medium that is nonlinear at the level of individual quanta, exhibiting strong absorption of photon pairs while remaining transparent to single photons. The quantum nonlinearity is obtained by coherently coupling slowly propagating photons [3][4][5] to strongly interacting atomic Rydberg states [6][7][8][9][10][11][12] in a cold, dense atomic gas 13 . Our approach opens the door for quantum-byquantum control of light fields, including single-photon switching 14 , all-optical deterministic 1 quantum logic 15 , and the realization of strongly correlated many-body states of light 16 .…”

mentioning

confidence: 99%

“…EIT nonlinearities at the few-photon level have been previously observed without using strongly interacting atomic states by means of strong transverse confinement of the light 28,29 . The interactions between cold Rydberg atoms have been explored in ensembles [6][7][8][9][10] and have been used to realize quantum logic gates between two Rydberg atoms 11,12,24 . Giant optical nonlinearities using Rydberg EIT 14,22,23 have been observed in a classical, multi-photon regime 13 .…”

mentioning

confidence: 99%

Quantum nonlinear optics with single photons enabled by strongly interacting atoms

Peyronel

Firstenberg

Liang

et al. 2012

Nature

814

887

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The realization of strong nonlinear interactions between individual light quanta (photons) is a long-standing goal in optical science and engineering 1, 2 that is both of fundamental and technological significance. In conventional optical materials, the nonlinearity at light powers corresponding to single photons is negligibly weak. Here we demonstrate a medium that is nonlinear at the level of individual quanta, exhibiting strong absorption of photon pairs while remaining transparent to single photons. The quantum nonlinearity is obtained by coherently coupling slowly propagating photons [3][4][5] to strongly interacting atomic Rydberg states [6][7][8][9][10][11][12] in a cold, dense atomic gas 13 . Our approach opens the door for quantum-byquantum control of light fields, including single-photon switching 14 , all-optical deterministic 1 quantum logic 15 , and the realization of strongly correlated many-body states of light 16 .Recently, remarkable advances have been made towards optical systems that are nonlinear at the level of individual photons. The most promising approaches have used high-finesse optical cavities to enhance the atom-photon interaction probability 2,[17][18][19][20][21] . In contrast, our present method is cavity-free and is based on mapping photons onto atomic states with strong interactions in an extended atomic ensemble 13,14,22,23 . The central idea is illustrated in Fig. 1, where a quantum probe field incident onto a cold atomic gas is coupled to high-lying atomic states (Rydberg levels 24 ) by means of a second, stronger laser field (control field). For a single incident probe photon, the control field induces a transparency window in the otherwise opaque medium via Electromagnetically Induced Transparency (EIT), and the probe photon travels at much reduced speed in the form of a coupled excitation of light and matter (Rydberg polariton). However, in stark contrast to conventional EIT 5 , if two probe photons are incident onto the Rydberg EIT medium, the strong interaction between two Rydberg atoms tunes the EIT transition out of resonance, thereby destroying the EIT and leading to absorption 14,22,23, 25, 26 . The experimental demonstration of an extraordinary optical material exhibiting strong two-photon attenuation in combination with single-photon transmission is the central result of this work.The quantum nonlinearity can be viewed as a photon-photon blockade mechanism that prevents the transmission of any multi-photon state. It arises from the Rydberg excitation blockade 27 , which precludes the simultaneous excitation of two Rydberg atoms that are separated by less than a blockade radius r b (see Figure 1). During the optical excitation, an incident single photon is 2 converted, under the EIT conditions, into a Rydberg polariton inside the medium. However, due to the Rydberg blockade, a second polariton cannot travel within a blockade radius from the first one, and EIT is destroyed. Accordingly if the second photon approaches the single Rydberg polariton, it will be signific...

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“…Furthermore, dipolar interactions between highly excited atoms have been proposed as a mechanism for 'Rydberg blockade' 6,7 , which might provide a novel approach to a number of quantum protocols [8][9][10][11] . Dipolar interactions between Rydberg atoms were observed several decades ago 12 and have been studied recently in a many-body regime using cold atoms [13][14][15][16][17][18] . However, to harness Rydberg blockade for controlled quantum dynamics, it is necessary to achieve strong interactions between single pairs of atoms.…”

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confidence: 99%

Observation of Rydberg blockade between two atoms

et al. 2009

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Blockade interactions whereby a single particle prevents the flow or excitation of other particles provide a mechanism for control of quantum states, including entanglement of two or more particles. Blockade has been observed for electrons 1-3 , photons 4 and cold atoms 5 . Furthermore, dipolar interactions between highly excited atoms have been proposed as a mechanism for 'Rydberg blockade' 6,7 , which might provide a novel approach to a number of quantum protocols [8][9][10][11] . Dipolar interactions between Rydberg atoms were observed several decades ago 12 and have been studied recently in a many-body regime using cold atoms [13][14][15][16][17][18] . However, to harness Rydberg blockade for controlled quantum dynamics, it is necessary to achieve strong interactions between single pairs of atoms. Here, we demonstrate that a single Rydberg-excited rubidium atom blocks excitation of a second atom located more than 10 µm away. The observed probability of double excitation is less than 20%, consistent with a theoretical model of the Rydberg interaction augmented by Monte Carlo simulations that account for experimental imperfections.The mechanism of Rydberg blockade is shown in Fig. 1a. Two atoms, one labelled 'control' and the other 'target', are placed in proximity with each other. The ground state |1 and Rydberg state |r of each atom form a two-level system that is coupled by laser beams with Rabi frequency Ω . Application of a 2π pulse (Ωt = 2π with t being the pulse duration) on the target atom results in excitation and de-excitation of the target atom giving a phase shift of π on the quantum state, |1 t → −|1 t . If the control atom is excited to the Rydberg state before application of the 2π pulse, the dipole-dipole interaction |r c ↔ |r t shifts the Rydberg level by an amount B that detunes the excitation of the target atom so that it is blocked and |1 t → |1 t . Thus, the excitation dynamics and phase of the target atom depend on the state of the control atom. Combining this Rydberg-blockade-mediated controlled-phase operation 6 with π/2 single-atom rotations between states |0 t and |1 t of the target will implement the CNOT gate between two atoms. We have previously demonstrated the ability to carry out ground-state rotations at individual trapping sites 19 , as well as coherent excitation from ground to Rydberg states at a single site 20 . Here, we describe experiments that demonstrate the Rydberg blockade effect between two neutral atoms separated by more than 10 µm, which is an enabling step towards creation of entangled atomic states. Previous demonstrations of neutral-atom entanglement have relied on shortrange collisions at length scales characterized by a low-energy scattering length of about 10 nm (refs 21,22). Our results, using laser-cooled and optically trapped 87 Rb, extend the distance for strong two-atom interactions by three orders of magnitude, and place us in a regime where the interaction distance is large compared with 1 µm, which is the characteristic wavelength of light needed for...

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Local Blockade of Rydberg Excitation in an Ultracold Gas

Cited by 570 publications

References 15 publications

Radiative and collisional processes in translationally cold samples of hydrogen Rydberg atoms studied in an electrostatic trap

Radiative and collisional processes in translationally cold samples of hydrogen Rydberg atoms studied in an electrostatic trap

Quantum nonlinear optics with single photons enabled by strongly interacting atoms

Observation of Rydberg blockade between two atoms

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