Direct Frequency Comb Spectroscopy of Trapped Ions

Wolf, A.; Berg, S. A. van den; Ubachs, Wim; Eikema, K.S.E.

doi:10.1103/physrevlett.102.223901

Cited by 37 publications

(46 citation statements)

References 31 publications

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“…This is demonstrated on a laser-cooled crystal of calcium ions, in which the dipoleforbidden 4s 2 S 1=2 -3d 2 D 5=2 transition at 729 nm (natural linewidth 0:14 Hz) is induced with DFCS. On this transition, one can potentially reach hertz-level accuracy, as was shown previously by Chwalla et al using cw laser excitation [13].In our experiment, calcium ions are produced by twophoton excitation involving a frequency-doubled portion of the FC [9]. The created ions are trapped in a segmented linear Paul trap (Fig.…”

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confidence: 59%

“…In addition, the development of broadband titaniumdoped sapphire FC lasers with a wavelength span of hundreds of nanometers [4,5] makes high-accuracy frequency calibration possible over a very wide wavelength range. These FCs can be employed to calibrate an additional laser that is used for excitation, but it is also possible to directly use the light of the comb modes to perform the metrology [6][7][8][9]. This technique of direct FC spectroscopy (DFCS) is advantageous in that the full comb spectrum is available for excitation, without the need for an additional probe laser.…”

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confidence: 99%

“…Furthermore, different ionic species can be trapped simultaneously and be sympathetically cooled and detected by the laser-cooled ions [10,11]. The application of DFCS to trapped ions [9] thus facilitates spectroscopy on various ionic transitions in a single measurement setup. To our knowledge, the possibility of DFCS of trapped ions has been demonstrated only for strong resonance lines.…”

mentioning

confidence: 99%

“…In our experiment, calcium ions are produced by twophoton excitation involving a frequency-doubled portion of the FC [9]. The created ions are trapped in a segmented linear Paul trap (Fig.…”

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Direct frequency-comb spectroscopy of a dipole-forbidden clock transition in trapped Ca^+40 ions

et al. 2010

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We demonstrate direct frequency-comb (FC) spectroscopy of the dipole-forbidden 4s 2 S 1=2 -3d 2 D 5=2 transition in trapped 40 Ca þ ions using an unamplified FC laser. The excitation is detected with nearly 100% efficiency using a shelving scheme in combination with single-ion imaging. The method demonstrated here has the potential to reach hertz-level accuracy, if a hertz-level linewidth FC is used in combination with confinement in the Lamb-Dicke regime. © 2010 Optical Society of America OCIS codes: 300.6520, 120.3940, 140.7090.Optical frequency combs (FCs) provide a direct link between optical and microwave frequencies [1,2]. This link enables carrying the accuracy of a microwave frequency standard to the optical domain, or transferring the extreme accuracy achieved in optical spectroscopy (currently reaching below the 10 −17 level [3]) to any other part of the optical spectrum and to the microwave domain. In addition, the development of broadband titaniumdoped sapphire FC lasers with a wavelength span of hundreds of nanometers [4,5] makes high-accuracy frequency calibration possible over a very wide wavelength range. These FCs can be employed to calibrate an additional laser that is used for excitation, but it is also possible to directly use the light of the comb modes to perform the metrology [6][7][8][9]. This technique of direct FC spectroscopy (DFCS) is advantageous in that the full comb spectrum is available for excitation, without the need for an additional probe laser.Trapped laser-cooled ions provide an ideal system for DFCS, as they allow for long interaction times. Furthermore, different ionic species can be trapped simultaneously and be sympathetically cooled and detected by the laser-cooled ions [10,11]. The application of DFCS to trapped ions [9] thus facilitates spectroscopy on various ionic transitions in a single measurement setup. To our knowledge, the possibility of DFCS of trapped ions has been demonstrated only for strong resonance lines. The range of applicability of this method would be greatly extended if also weak and narrow transitions could be detected. For example, such a "clock" transition could be used as an in situ frequency reference for the calibration of other transitions in ions or as a probe for external fields in the ion trap. The concept of DFCS on narrow transitions has been investigated for cold neutral calcium atoms on a transition with a linewidth of 374 Hz, using the amplified modes of an FC [12]. In this Letter, we show that DFCS can be performed on significantly weaker transitions, using an ion trap and even without amplification of the FC laser. This is demonstrated on a laser-cooled crystal of calcium ions, in which the dipoleforbidden 4s 2 S 1=2 -3d 2 D 5=2 transition at 729 nm (natural linewidth 0:14 Hz) is induced with DFCS. On this transition, one can potentially reach hertz-level accuracy, as was shown previously by Chwalla et al. using cw laser excitation [13].In our experiment, calcium ions are produced by twophoton excitation involving a frequency-double...

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confidence: 59%

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confidence: 99%

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confidence: 99%

mentioning

confidence: 99%

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Direct frequency-comb spectroscopy of a dipole-forbidden clock transition in trapped Ca^+40 ions

et al. 2010

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“…Note that this requires a comb whose spectrum spans at least an octave, or broadening the light with a nonlinear fiber. This stabilization enables direct frequency comb spectroscopy, accurately revealing the atomic level structure of neutral atoms [30,31] and ions [32,33].We rather work on the time-domain image of the pulse train. The effect of the offset frequency is to change the CEP from pulse to pulse, Fig.…”

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Phase Stabilization of a Frequency Comb using Multipulse Quantum Interferometry

2014

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From the interaction between a frequency comb and an atomic qubit, we derive quantum protocols for the determination of the carrier-envelope offset phase, using the qubit coherence as a reference, and without the need of frequency doubling or an octave spanning comb. Compared with a trivial interference protocol, the multipulse protocol results in a polynomial enhancement of the sensitivity OðN −2 Þ with the number N of laser pulses involved. We specialize the protocols using optical or hyperfine qubits, Λ schemes, and Raman transitions, and introduce methods where the reference is another phase-stable cw laser or frequency comb. DOI: 10.1103/PhysRevLett.112.073603 PACS numbers: 42.50.St, 03.67.Ac, 07.60.Ly, 42.62.Eh Quantum physics has experienced a universally recognized [1] progress in the control and observation of individual quantum systems. In this respect, trapped ions [2,3] are one of the most mature setups, with unbeaten precision in the realization of single- [4] and two-qubit [5] unitaries and measurements [6,7], closely followed by neutral atoms [8]. This spectacular progress underlies a number of "spin offs," such as the characterization of atomic properties using entanglement [9] or the development of quantum algorithms and protocols [10][11][12] for studying molecular ions. The synergy is even more advanced in the field of metrology, with accurate atomic clocks assisted by quantum gates [13,14] or the use of atomic squeezing for enhanced magnetometry [15,16].Despite the exquisite precision of atomic, molecular and optical (AMO) systems, the control and detection time scales (∼10 μs to 10 ms) prevented using these techniques for studying ultrafast processes. In this work, we show that the speed of AMO setups is sufficient to accurately stabilize the carrier-envelope offset phase (CEP) of a frequency comb (FC). CEP effects are relevant for few-cycle pulses, though effects in multicycle pulses have also been reported [17]. The first observation of CEP effects was reported in the spatial asymmetry of above-threshold ionization from Kr gas [18] and in x-ray emission from Ne [19]. The direction of photocurrents injected in semiconductors is also controlled by the CEP [20,21] and the absolute CEP of single pulses was recently measured [22]. The study of the CEP has been generally centered on its spectral components [23], while only a few reports have addressed timedomain measurements of the relative phase of successive pulses in a train [24,25]. The methods presented below follow this less-beaten path.Let us introduce the notion of "multipulse quantum interferometry" (MPQI), where an atom acts as a nonlinear, fast-response detector that efficiently measures the differences between ultrashort laser pulses. Modeling the atom-pulse interaction as a sequence of unitaries fU i g N i¼1through a suitable reordering of the pulses, additional gates, and measurements, we build protocols that accurately determine the differences among the pulses, or the properties of individual pulses themselves. Compared with ...

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Femtosecond Optical Frequency Combs

Udem

Holzwarth

Hänsch

2013

Ultrafast Nonlinear Optics

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Abstract. A laser frequency comb allows the conversion of the very rapid oscillations of visible light of some 100's of THz down to frequencies that can be handled with conventional electronics. This capability has enabled the most precise laser spectroscopy experiments yet that allowed to test quantum electrodynamics, to determine fundamental constants and to search for possible slow changes of these constants. Using an optical frequency reference in combination with a laser frequency comb has made it possible to construct all optical atomic clocks, that are now outperforming even the best cesium atomic clocks. In future direct frequency comb spectroscopy might enable high resolution laser spectroscopy in the extreme ultraviolet for the first time. Frequency combs are also used to calibrate astronomical spectrographs and might reach an accuracy that is sufficient to observe the expansion of the universe in real time.

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Direct Frequency Comb Spectroscopy of Trapped Ions

Cited by 37 publications

References 31 publications

Direct frequency-comb spectroscopy of a dipole-forbidden clock transition in trapped Ca^+40 ions

Direct frequency-comb spectroscopy of a dipole-forbidden clock transition in trapped Ca^+40 ions

Phase Stabilization of a Frequency Comb using Multipulse Quantum Interferometry

Femtosecond Optical Frequency Combs

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