[81] Experimental demonstration of composite stimulated Raman adiabatic passage
Alexander Bruns, Genko T. Genov, Marcel Hain, Nikolay V. Vitanov, and Thomas Halfmann
Phys. Rev. A 98, 053413 (2018)
https://doi.org/10.1103/PhysRevA.98.053413

[80] Phase-matched harmonic generation in gas-filled waveguides in the vicinity of a multiphoton resonance
Patric Ackermann, Xavier Laforgue, Mario Hilbig, Maximilian Schilder, and Thomas Halfmann
J. Opt. Soc. Am. B 35, 2 468-480 (2018)
https://doi.org/10.1364/JOSAB.35.000468

[79] Laser frequency stabilization by bichromatic saturation absorption spectroscopy
Genko Genov, Tim E. Lellinger, Thomas Halfmann, and Thorsten Peters
J. Opt. Soc. Am. B 34, 9 2018-2030 (2017)
https://doi.org/10.1364/JOSAB.34.002018

[78] Robust not gate by single-shot-shaped pulses: Demonstration of the efficiency of the pulses in rephasing atomic coherences
Leo Van-Damme, Daniel Schraft, Genko T. Genov, Dominique Sugny, Thomas Halfmann, and Stéphane Guérin
Phys. Rev. Lett. 118, 133202 (2017)
https://doi.org/10.1103/PhysRevA.96.022309

[77] Arbitrarily accurate pulse sequences for robust dynamical decoupling
Genko T. Genov, Daniel Schraft, Nikolay V. Vitanov, and Thomas Halfmann
Phys. Rev. Lett. 118, 133202 (2017)
https://doi.org/10.1103/PhysRevLett.118.133202

[76] Dispersion-enhanced third-harmonic microscopy
C. Stock, K. Zlatanov, and T. Halfmann
Opt. Commun. 393, 289 (2017)
DOI:10.1016/j.optcom.2017.02.059

[75] Stationary light pulses and narrowband light storage in a laser-cooled ensemble loaded into a hollow-core fiber
Frank Blatt, Lachezar S. Simeonov, Thomas Halfmann, and Thorsten Peters
Phys. Rev. A 94, 043833 (2016)
https://doi.org/10.1103/PhysRevA.94.043833

[74] Stopped light at high storage efficiency in a Pr3+:Y2SiO5 crystal
D. Schraft, M. Hain, N. Lorenz, and T. Halfmann
Phys. Rev. Lett. 116, 073602 (2016)
http://dx.doi.org/10.1103/PhysRevLett.116.073602

[73] Phase-insensitive storage of coherences by reversible mapping onto long-lived populations
S. Mieth, G. T. Genov, L. P. Yatsenko, N. V. Vitanov, and T. Halfmann
Phys. Rev. A 93, 012312 (2016)
http://dx.doi.org/10.1103/PhysRevA.93.012312

[72] Correction of arbitrary field errors in population inversion of quantum systems by universal composite pulses
G. Genov, D. Schraft, T. Halfmann, and N.V. Vitanov
Phys. Rev. Lett. 113, 043001 (2014)
http://dx.doi.org/10.1103/PhysRevLett.113.043001

[71] Strong quantum interferences in frequency up-conversion towards short vacuum-ultraviolet radiation pulses
P. Ackermann, A. Scharf, and T. Halfmann
Phys. Rev. A 89, 063804 (2014)
http://dx.doi.org/10.1103/PhysRevA.89.063804

[70] Coherence time extension in Pr3+:Y2SiO5 by self-optimized magnetic fields and dynamical decoupling
G. Heinze, C. Hubrich, and T. Halfmann
Phys. Rev. A 89, 053825 (2014)
http://dx.doi.org/10.1103/PhysRevA.89.053825

[69] Tunable, continuous-wave optical parametric oscillator with more than 1W output power in the orange visible spectrum
S. Mieth, A. Henderson, and T. Halfmann
Opt. Expr. 22, 11182 (2014)
http://dx.doi.org/10.1364/OE.22.011182

[68] A one-dimensional ultracold medium of extreme optical depth
F. Blatt, T. Halfmann, and T. Peters
Opt. Lett. 39, 446 (2014)
http://dx.doi.org/10.1364/OL.39.000446

[67] Experimental demonstration of composite adiabatic passage
D. Schraft, G.T. Genov, N.V. Vitanov, and T. Halfmann
Phys. Rev. A. 88, 063406 (2013)
http://dx.doi.org/10.1103/PhysRevA.88.063406

[66] Stopped light and image storage by electromagnetically induced transparency up to the regime of one minute
G. Heinze, C. Hubrich, and T. Halfmann
Phys. Rev. Lett. 111, 033601 (2013)
http://dx.doi.org/10.1103/PhysRevLett.111.033601

[65] Spatial emission profiles at different interface orientations in third harmonic generation microscopy
U. Petzold, C.Wenski, A. Romanenko, and T. Halfmann
J. Opt. Soc. Am. B 30, 1725 (2013)
http://dx.doi.org/10.1364/JOSAB.30.001725

[64] Rephasing of optically driven atomic coherences by rapid adiabatic passage in Pr3+:Y2SiO5
S. Mieth, D. Schraft, P. Yatsenko, and T. Halfmann
Phys. Rev. A 86, 063404 (2012)
http://dx.doi.org/10.1103/PhysRevA.86.063404

[63] Dependence of combustion dynamics in a gasoline engine upon the in-cylinder flow field
determined by high-speed particle imaging velocimetry
M. Buschbeck, N. Bittner, T. Halfmann, and S. Arndt
Exp. Fluids 53, 1701 (2012)
http://dx.doi.org/10.1007/s00348-012-1384-3

[62] Multiplexed image storage by electromagnetically induced transparency in a solid
G. Heinze, N. Rentzsch, and T. Halfmann
Phys. Rev. A 86, 053837 (2012)
http://dx.doi.org/10.1103/PhysRevA.86.053837

[61] Variable ultra-broadband and narrowband composite polarization retarders
T. Peters, S.S. Ivanov, D. Englisch, A. Rangelov, N.V. Vitanov, and T. Halfmann
Appl. Opt. 51, 7466 (2012)
http://dx.doi.org/10.1364/AO.51.007466

[60] Imaging diffusion in a microfluidic device by third harmonic microscopy
U. Petzold, A. Büchel, S. Hardt, and T. Halfmann
Exp. Fluids 53, 777 (2012)
http://dx.doi.org/10.1007/s00348-012-1321-5

[59] Laser-induced breakdown spectroscopy for lambda quantification in a direct-injection engine
M. Buschbeck, F. Büchler, T. Halfmann, and S. Arndt
Spectrochimica Acta B 74, 103 (2012) 
http://dx.doi.org/10.1016/j.sab.2012.06.051

[58] Thermometry of ultracold atoms by electromagnetically induced transparency
T. Peters, B. Wittrock, F. Blatt, T. Halfmann and L. P. Yatsenko
Phys. Rev. A 85, 063416 (2012) 
http://dx.doi.org/10.1103/PhysRevA.85.063416

[57]Resonantly-enhanced harmonic generation in Argon
P. Ackermann, H. Münch and T. Halfmann
Opt. Expr. 20, 13824 (2012) 
http://dx.doi.org/10.1364/OE.20.013824

[56] Highly efficient broadband conversion of light polarization by composite retarders
S. S. Ivanov, A. A. Rangelov, N. V. Vitanov, T. Peters and T. Halfmann
J. Opt. Soc. Am. A 29, 265 (2012) 
http://dx.doi.org/10.1364/JOSAA.29.000265

[55] Effects of laser polarization and interface orientation in harmonic generation microscopy
U. Petzold, A. Büchel and T. Halfmann
Opt. Expr. 20, 3654 (2012) 
http://dx.doi.org/10.1364/OE.20.003654

[54] Storage and retrieval of coherent optical information in atomic populations
M.V. Gromovyi, V.I. Romanenko, S. Mieth, T. Halfmann and L.P. Yatsenko
Opt. Comm. 284, 5710 (2011)
http://dx.doi.org/10.1016/j.optcom.2011.08.005

[53] Control of dark-state polariton collapses in a doped crystal
G. Heinze, S. Mieth, and T. Halfmann
Phys. Rev. A 84, 013827 (2011)
http://dx.doi.org/10.1103/PhysRevA.84.013827

[52] Logic operations in a doped solid driven by stimulated Raman adiabatic passage
F. Beil, F. Remacle, R. Levine, and T. Halfmann
Phys. Rev. A 83, 033421 (2011)
http://dx.doi.org/10.1103/PhysRevA.83.033421

[51] Adiabatically driven frequency conversion towards short extreme-ultraviolet radiation pulses
S. Chakrabarti, H. Münch, and T. Halfmann
Phys. Rev. A 82, 063817 (2010)
http://dx.doi.org/10.1103/PhysRevA.82.063817

[50] Coherent Control of Frequency Conversion towards Short (Picosecond) Vacuum-Ultraviolet Radiation Pulses
H. Münch, S. Chakrabarti, and T. Halfmann
Phys. Rev. A 82, 033821 (2010)
http://dx.doi.org/10.1103/PhysRevA.82.033821

[49] Light storage in a doped solid enhanced by feedback-controlled pulse shaping
F. Beil, M. Buschbeck, G. Heinze, and T. Halfmann
Phys. Rev. A 81, 053801 (2010)
http://dx.doi.org/10.1103/PhysRevA.81.053801

[48] Storage of images in atomic coherences in a rare-earth-ion-doped solid
G. Heinze, A. Rudolf, F. Beil, and T. Halfmann
Phys. Rev. A 81, 011401(R) (2010)
http://dx.doi.org/10.1103/PhysRevA.81.011401

[47] Theory of bright state stimulated Raman adiabatic passage
G. G. Grigoryan, G. V. Nikoghosyan, T. Halfmann, Y. T. Pashayan-Leroy, C. Leroy, and S.Guerin
Phys. Rev. A 80, 033402 (2009)
http://dx.doi.org/10.1103/PhysRevA.80.033402

[46] Photorefractive spatial solitons as waveguiding elements for optical telecommunication
M. Tiemann, T. Halfmann, and T. Tschudi,
Opt. Comm. 282, 3612 (2009)
http://dx.doi.org/10.1016/j.optcom.2009.05.077

[45] Optically Driven Atomic Coherences in a Pr:YSO crystal
F. Beil, J. Klein and T. Halfmann
Phot. Nanostr. 7, 32 (2009)
http://dx.doi.org/10.1016/j.photonics.2008.11.006

[44] Experimental Investigations of Stimulated Raman Adiabatic Passage in a Doped Solid
J. Klein, F. Beil and T. Halfmann,
Phys. Rev. A 78, 033416 (2008)
http://dx.doi.org/10.1103/PhysRevA.78.033416

[43] Stark-Chirped Rapid Adiabatic Passage among a Three State Molecular System: Experimental and Numerical Investigations
M. Oberst, H. Münch, G. Grigoryan, and T. Halfmann
Phys. Rev. A 78, 033409 (2008)
http://dx.doi.org/10.1103/PhysRevA.78.033409

[42] Electromagnetically induced transparency and retrieval of light pulses in a Pr:YSO crystal
F. Beil, J. Klein, G. Nikoghosyan, and T. Halfmann
Special issue J. Phys. B “Coherent Control”, edt. M. Shapiro, T. Baumert, and H. Fielding,
J. Phys. B 41, 074001 (2008)
http://dx.doi.org/10.1088/0953-4075/41/7/074001

[41] Efficient Coherent Population Transfer in NO Molecules by Stark-Chirped Rapid Adiabatic Passage in Three State Quantum Systems
M. Oberst, H. Münch, and T. Halfmann
Phys. Rev. Lett. 99, 173001 (2007)
http://dx.doi.org/10.1103/PhysRevLett.99.173001

[40] Robust Population Transfer by Stimulated Raman Adiabatic Passage in a Pr:YSO Crystal
J. Klein, F. Beil, and T. Halfmann
Phys. Rev. Lett. 99, 113003 (2007)
http://dx.doi.org/10.1103/PhysRevLett.99.113003

[39] Rapid Adiabatic Passage in a Pr:YSO Crystal
J. Klein, F. Beil, and T. Halfmann
Special issue J. Phys. B “Light Control at the Nanoscale”, edt. by P. Kral and M. Shapiro,
J. Phys. B 40, S345 (2007)
http://dx.doi.org/10.1088/0953-4075/40/11/S08

[38] Stimulated Raman Adiabatic Passage via the Ionization Continuum in Helium: Experiment and Theory
T. Peters and T. Halfmann
Opt. Comm. 271, 475 (2007)
http://dx.doi.org/10.1016/j.optcom.2006.10.055

[37] Trace Isotope Detection Enhanced by Coherent Elimination of Power Broadening
A. Peralta Conde, L. Brandt, and T. Halfmann
Phys. Rev. Lett. 97, 243004 (2006)
http://dx.doi.org/10.1103/PhysRevLett.97.243004

[36] Lineshapes of the Even mp5 1/2 n(p’/f’) Autoionizing Resonances of Ar, Kr and Xe
I. D. Petrov, T. Peters, T. Halfmann, S. Aloise, P. O'Keeffe, M. Meyer, V. L. Sukhorukov, and H. Hotop
Eur. Phys. J. D. 40, 181 (2006)
http://dx.doi.org/10.1140/epjd/e2006-00153-8

[35] Exploration of Electronic Quadrupole States in Atomic Clusters by Two-Photon Processes
V. O. Nesterenko, P.G. Reinhard, T. Halfmann and E Suraud
J. Phys. B 39, 3905 (2006)
http://dx.doi.org/10.1088/0953-4075/39/18/020

[34] Two-Photon Excitation of Low-Lying Electronic Quadrupole States in Atomic Clusters
V.O. Nesterenko, P.G. Reinhard, T. Halfmann, and L.I. Pavlov
Phys. Rev. A 73, 021201 (2006)
http://dx.doi.org/10.1103/PhysRevA.73.021201

[33] Preparation of Nondegenerate Coherent Superpositions in a Three-State Ladder System Assisted by Stark Shifts
N. Sangouard, L.P. Yatsenko, B.W. Shore, T. Halfmann
Phys. Rev. A 73, 043415 (2006)
http://dx.doi.org/10.1103/PhysRevA.73.043415

[32]Enhanced Four-Wave Mixing in Mercury Isotopes, Prepared by Stark-Chirped Rapid Adiabatic Passage
M. Oberst, J. Klein, and T. Halfmann
in special issue Opt. Comm.,“Quantum Control of Light and Matter”, edt. by T. Halfmann
Opt. Comm. 264, 463 (2006)
http://dx.doi.org/10.1016/j.optcom.2005.12.084

[31] Stark-Shift-Chirped Rapid-Adiabatic-Passage Technique Among Three States
A. A. Rangelov, N. V. Vitanov, L. P. Yatsenko, B. W. Shore, T. Halfmann, and K. Bergmann
Phys. Rev. A 72, 053403 (2005)
http://dx.doi.org/10.1103/PhysRevA.72.053403

[30] Experimental Demonstration of Population Inversion Driven by Retroreflection-Induced Bichromatic Adiabatic Passage
A. Peralta-Conde, J. Klein, M. Oberst, L.P. Yatsenko, and T. Halfmann
Phys. Rev. A 72, 053808 (2005)
http://dx.doi.org/10.1103/PhysRevA.72.053808

[29] Experimental Demonstration of Selective Coherent Population Transfer via a Continuum
T. Peters, L.P. Yatsenko, and T. Halfmann
Phys. Rev. Lett. 95, 103601 (2005)
http://dx.doi.org/10.1103/PhysRevLett.95.103601

[28] Two-Photon Excitation of the Metastable 2s State of Hydrogen Assisted by Laser-Induced Chirped Stark Shifts and Continuum Structure
L.P. Yatsenko, V. Romanenko, B.W. Shore, T. Halfmann and K. Bergmann
Phys. Rev. A 71, 033418 (2005)
http://dx.doi.org/10.1103/PhysRevA.71.033418

[27] Behavior of high-order stimulated Raman scattering in a highly transient regime
E. Sali, P. Kinsler, G.H.C. New, K.J. Mendham, T. Halfmann, J.W.G. Tisch and J.P. Marangos,
Phys. Rev. A 72, 013813 (2005)
http://dx.doi.org/10.1103/PhysRevA.72.013813

[26] Experimental and Theoretical Investigation of even mp5 1/2 np’ Autoionizing Resonances of Rare Gas Atoms
T. Peters, T. Halfmann, U. Even, A. Wünnenberg, I.D. Petrov, V.L. Sukhorukov, and H. Hotop
J. Phys. B. 38, 51 (2005)
http://dx.doi.org/10.1088/0953-4075/38/2/004

[25] Preparation of Coherent Superposition in a Three-State System by Adiabatic Passage
N. Sangouard, S. Guerin, L.P. Yatsenko, and T. Halfmann
Phys. Rev. A 70, 013415 (2004)
http://dx.doi.org/10.1103/PhysRevA.70.013415

[24] High-order Stimulated Raman Scattering in a Highly Transient Regime Driven by a Pair of Ultrashort Pulses
E.Sali, K.J. Mendham, J.W.G. Tisch, T.Halfmann, and J.P.Marangos
Opt. Lett. 29, 495 (2004)
http://dx.doi.org/10.1364/OL.29.000495

[23] Enhancement of Third-Harmonic Generation by Stark-Chirped Rapid Adiabatic Passage
T. Rickes, J.P. Marangos, and T. Halfmann
Opt. Comm. 227, 133 (2003)
http://dx.doi.org/10.1016/j.optcom.2003.09.036

[22] Investigation of Auto-Ionizing States in Xenon by Resonantly Enhanced Multi-Photon Ionization
M. Stellpflug, M. Johnsson, I. D. Petrov, and T. Halfmann
Eur. Phys. J. D 23, 35 (2003)
http://dx.doi.org/10.1140/epjd/e2003-00021-1

[21] Lineshapes in Coherent Two-Photon Excitation
T. Halfmann, T. Rickes, N. Vitanov, and K. Bergmann
Opt. Comm. 220, 353 (2003)
http://dx.doi.org/10.1016/S0030-4018(03)01368-3

[20] Analytical Study of Four-Wave Mixing with Large Atomic Coherence
E. Korsunsky, T. Halfmann, J.P. Marangos, and K. Bergmann
Eur. Phys. J. D 23, 167 (2003)
http://dx.doi.org/10.1140/epjd/e2003-00029-5

[19] Nonlinear-Optical Vacuum-Ultraviolet Generation at Maximum Coherence Controlled by a Laser-Induced Stark Chirp of Two-Photon Resonance
S.A. Myslivets, A.K. Popov and V.V. Kimberg, T. Halfmann, J.P. Marangos, T. F. George
Opt. Comm. 209, 335 (2002)
http://dx.doi.org/10.1016/S0030-4018(02)01731-5

[18] Laser-Induced Continuum Structure in the Two Ionization Continua of Xenon
K. Böhmer, T. Halfmann, L.P. Yatsenko, D. Charalambidis, A. Horsmans, and K. Bergmann
Phys. Rev. A 66, 013406 (2002)
http://dx.doi.org/10.1103/PhysRevA.66.013406

[17] Probing Attosecond Pulse Trains using Phase Control Techniques
E. Hertz, N.A. Papadogiannis, G. Nersisyan, C. Kalpouzos and D. Charalambidis, T. Halfmann, G.D. Tsakiris
Phys. Rev. A 64, 051801(R) (2001)
http://dx.doi.org/10.1103/PhysRevA.64.051801

[16] Power Broadening Revisited: Theory and Experiment
N.V. Vitanov, B.W. Shore, L.P.Yatsenko, T. Halfmann, T. Rickes, K. Böhmer, and K. Bergmann
Opt. Comm. 199, 117 (2001)
http://dx.doi.org/10.1016/S0030-4018(01)01495-X

[15] Coherent Population Trapping involving Rydberg States in Xenon probed by Ionization Suppression
T. Halfmann, K. Böhmer, L.P. Yatsenko, A. Horsmans and K. Bergmann
Eur. Phys. J. D 17, 113 (2001)
http://dx.doi.org/10.1007/s100530170044

[14] Laser-Induced Population Transfer by Adiabatic Passage Techniques
N.V. Vitanov, T. Halfmann, B.W. Shore, and K. Bergmann
Review Article, Ann. Rev. Phys. Chem. 52, 763 (2001)
http://dx.doi.org/10.1146/annurev.physchem.52.1.763

[13] Stimulated Hyper-Raman Adiabatic Passage III: Experiment
K. Böhmer, T. Halfmann, L.P. Yatsenko, B.W. Shore, and K. Bergmann,
Phys. Rev. A 64, 023404 (2001)
http://dx.doi.org/10.1103/PhysRevA.64.023404

[12] High Order Harmonic Generation from Organic Molecules in Ultra-Short Pulses
N. Hay, R. de Nalda, T. Halfmann, K.J. Mendham, M.B. Mason, M. Castillejo, and J.P.Marangos
Eur. Phys. J D 14, 231 (2001)
http://dx.doi.org/10.1007/s100530170221

[11] Pulse Length Dependence of High-Order Harmonic Generation in Dissociating Cyclic Organic Molecules
N. Hay, R. de Nalda, T. Halfmann, K.J. Mendham, M.B. Mason, M. Castillejo, and J.P.Marangos,
Phys. Rev. A 62, 041803(R) (2000)
http://dx.doi.org/10.1103/PhysRevA.62.041803

[10] Generation of Vacuum Ultraviolet Radiation by Sum Frequency Mixing of a Femtosecond and a Nanosecond Laser
T. Halfmann, N. Hay, J.W.G. Tisch, and J.P. Marangos
Opt. Comm. 182, 229 (2000)
http://dx.doi.org/10.1016/S0030-4018(00)00823-3

[9] A Source for a High-Intensity Pulsed Beam of Metastable Helium Atoms
T. Halfmann, J. Koensgen, and K. Bergmann
Meas. Sci. Technol. 11, 1510 (2000)
http://dx.doi.org/10.1088/0957-0233/11/10/312

[8] Efficient Adiabatic Population Transfer by Two-Photon Excitation Assisted by a Laser-Induced Stark Shift
T. Rickes, L.P.Yatsenko, S.Steuerwald, T. Halfmann, B.W.Shore, N.V.Vitanov, and K.Bergmann
J. Chem. Phys. 113, 534 (2000)
http://dx.doi.org/10.1063/1.481829

[7] Source of Metastable H(2s) Atoms using the Stark Chirped Rapid Adiabatic Passage Technique
L.P. Yatsenko, B.W. Shore, T. Halfmann, K. Bergmann, and A. Vardi
Phys. Rev. A 60, R4237 (1999)
http://dx.doi.org/10.1103/PhysRevA.60.R4237

[6] Photoionization Suppression by Continuum Coherence: Experiment and Theory
L.P. Yatsenko, T. Halfmann, B.W. Shore, and K. Bergmann
Phys. Rev. 59, 2926 (1999)
http://dx.doi.org/10.1103/PhysRevA.59.2926

[5] Population Trapping and Laser-Induced Continuum Structure in Helium: Experiment and Theory
T. Halfmann, L.P. Yatsenko, M. Shapiro, B.W. Shore, and K. Bergmann
Phys. Rev. A 58, R46 (1998)
http://dx.doi.org/10.1103/PhysRevA.58.R46

[4] Stimulated Hyper-Raman Adiabatic Passage II: Static Compensation of Dynamic Stark Shifts
S. Guerin, L.P.Yatsenko, T. Halfmann, B.W. Shore, and K. Bergmann
Phys. Rev. A 58, 4691 (1998)
http://dx.doi.org/10.1103/PhysRevA.58.4691

[3] Stimulated Hyper-Raman Adiabatic Passage I: The Basic Problem and Examples
L.P. Yatsenko, S. Guerin, T. Halfmann, K. Böhmer, B.W. Shore, and K. Bergmann
Phys. Rev. A 58, 4683 (1998)
http://dx.doi.org/10.1103/PhysRevA.58.4683

[2] Population Transfer through the Continuum using Laser-Controlled Stark Shifts
L.P. Yatsenko, R.G. Unanyan, K. Bergmann, T. Halfmann, and B.W. Shore
Opt. Comm. 135, 406 (1997)
http://dx.doi.org/10.1016/S0030-4018(96)00630-X

[1] Coherent Population Transfer and Dark Resonances in SO₂
T. Halfmann and K. Bergmann
J. Chem. Phys. 104, 7068 (1996)
http://dx.doi.org/10.1063/1.471424

[B02] Electromagnetically Induced Transparency
T. Halfmann and J.P. Marangos,
in “Handbook of Optics”, Vol. 4, edt. E.W. Van Stryland, McGraw-Hill Publ. Co. (2009)

[B01] Enhanced Frequency Conversion in Coherently Prepared Media
T. Halfmann
in “Recent research activities in chemical physics: From atomic scale to macroscale”,
edt. by A. F. Terzis and E. Paspalakis, Research Signpost (2009)