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Journal Papers

“Systematic study of rotational decoherence with a trapped-ion planar rotor”
N. Glikin, B. A. Stickler, R. Tollefsen, S. Mouradian, N. Yadav, E. Urban, K. Hornberger, H. Häffner

“3D-Printed Micro Ion Trap Technology for Scalable Quantum Information Processing”
S. Xu, X. Xia, Q. Yu, S. Khan, E. Megidish, B. You, B. Hemmerling, A. Jayich, J. Biener, H. Häffner

“Test of Causal Non-Linear Quantum Mechanics by Ramsey Interferometry on the Vibrational Mode of a Trapped Ion”
J. Broz, B. You, S. Khan, H. Häffner, D. E. Kaplan, S. Rajendran
Phys. Rev. Lett. 130, 200201 (2023), arXiv:2206.12976.

“Sample-efficient verification of continuously-parameterized quantum gates for small quantum processors”
R. Shaffer, H. Ren, E. Dyrenkova, C. G. Yale, D. S. Lobser, A. D. Burch, M. N. H. Chow, M. C. Revelle, S. M. Clark, H. Häffner
Quantum 7, 997 (2023), arXiv:2205.13074.

“Surrogate-based optimization for variational quantum algorithms”
R. Shaffer, L. Kocia, M. Sarovar
Phys. Rev. A 107, 032415 (2023), arXiv:2204.05451.

“Quantum simulation of weak-field light-matter interactions”
S. M. Young, H. Häffner, M. Sarovar
Phys. Rev. Research 5, 013027 (2023), arXiv.2112.07177.

“Feasibility study of quantum computing using trapped electrons”
Q. Yu, A. M. Alonso, J. Caminiti, K. M. Beck, R. T. Sutherland, D. Leibfried, K. J. Rodriguez, M. Dhital, B. Hemmerling, H. Häffner
Phys. Rev. A 105, 022420 (2022), arXiv:2112.04034.

“One- and two-qubit gate infidelities due to motional errors in trapped ions and electrons”
R. T. Sutherland, Q. Yu, K. M. Beck, H. Häffner
Phys. Rev. A 105, 022437 (2022), arXiv:2111.01913.

“Coupling two laser-cooled ions via a room-temperature conductor”
D. An, A. M. Alonso, C. Matthiesen, H. Häffner
Phys. Rev. Lett. 128, 063201 (2022), arXiv:2107.00851.
See also Physics Viewpoint by Christian Tomás Schmiegelow:
““Tin-Can Telephone” Connects Two Ions”, Physics 15, 16.

“Trapped electrons and ions as particle detectors”
D. Carney, H. Häffner, D. C. Moore, J. M. Taylor
Phys. Rev. Lett. 127, 061804 (2021), arXiv:2104.05737.

“Changes in electric-field noise due to thermal transformation of a surface ion trap”
M. Berlin-Udi, C. Matthiesen, P.N.T. Lloyd, A. M. Alonso, C. Noel, C. Orme, C.-E. Kim, V. Lordi, H. Häffner
Phys. Rev. B 106, 035409 (2022), arXiv:2103.04482.

“Quantum Sensing of Intermittent Stochastic Signals”
S. Mouradian, N. Glikin, E. Megidish, K.-I. Ellers, H. Häffner
Phys. Rev. A 103, 032419 (2021), arXiv:2010.03678.

“Materials Challenges for Trapped-Ion Quantum Computers”
K. R. Brown, J. Chiaverini, J. Sage, H. Häffner
Nat. Rev. Mater. 6, 709–711 (2021), arXiv:2009.00568.

“Trapping electrons in a room-temperature quadrupole trap”
C. Matthiesen, Q. Yu, J. Guo, A. M. Alonso, H. Häffner
Phys. Rev. X 11, 011019 (2021), arXiv:2005.06681.
See also Physics Focus story by Philip Ball:
“New Electron Trap Might Help Quantum Computers”, Physics 14, 16.

“Practical verification protocols for analog quantum simulators”
R. Shaffer, E. Megidish, J. Broz, W.-T. Chen, H. Häffner
npj Quantum Inf. 7, 46 (2021), arXiv:2003.04500.

“Distance scaling and polarization of electric-field noise in a surface ion trap”
D. An, C. Matthiesen, E. Urban, H. Häffner
Phys. Rev. A 100, 063405 (2019), arXiv:1906.06489.

“Coherent Control of the Rotational Degree of Freedom of a Two-Ion Coulomb Crystal”
E. Urban, N. Glikin, S. Mouradian, K. Krimmel, B. Hemmerling, H. Häffner
Phys. Rev. Lett. 123, 133202 (2019), arXiv:1903.05763.

“Entanglement enhanced precision test of local Lorentz invariance”
E. Megidish, J. Broz, N. Greene, H. Häffner
Phys. Rev. Lett. 122, 123605 (2019), arXiv:1809.09807.

“Electric-field noise from thermally-activated fluctuators in a surface ion trap”
C. Noel, M. Berlin-Udi, C. Matthiesen, J. Yu, Y. Zhou, V. Lordi, H. Häffner
Phys. Rev. A 99, 063427 (2019), arXiv:1809.05624.

“Surface trap with dc-tunable ion-electrode distance”
D. An, C. Matthiesen, A. Abdelrahman, M. Berlin-Udi, D. Gorman, S. Möller, E. Urban, H. Häffner
Review of Scientific Instruments 89, 093102 (2018), arXiv:1807.06043.

“New methods for testing Lorentz invariance with atomic systems”
R. Shaniv, R. Ozeri, M.S. Safronova, S.G. Porsev, V.A. Dzuba, V.V. Flambaum, H. Häffner
Phys. Rev. Lett. 120, 103202 (2018), arXiv:1712.09514.

“Engineering vibrationally-assisted energy transfer in a trapped-ion quantum simulator”
D.J Gorman, B. Hemmerling, E. Megidish, S.A. Möller, P. Schindler, M. Sarovar, H. Häffner
Phys. Rev. X 8, 011038 (2018), arXiv:1709.04064.

“Revealing quantum statistics with a pair of distant atoms”
C. F. Roos, A. Alberti, D. Meschede, P. Hauke, H. Häffner
Phys. Rev. Lett. 119, 160401 (2017), arXiv:1706.04231.

“Spin readout of trapped electron qubits”
P. Peng, C. Matthiesen, H. Häffner
Phys. Rev. A 95, 012312 (2017), arXiv:1611.00130.

“Local probe of single phonon dynamics in warm ion crystals”
A. Abdelrahman, O. Khosravani, M. Gessner, H.-P. Breuer, A. Buchleitner, D.J Gorman, R. Masuda, T. Pruttivarasin, M. Ramm, P. Schindler, H. Häffner
Nat. Commun. 8, 15712 (2017), arXiv:1610.04927.

“Realization of translational symmetry in trapped cold ion rings”
H.K. Li, E. Urban, C. Noel, A. Chuang, Y. Xia, A. Ransford, B. Hemmerling, Y.Wang, T. Li, H. Häffner, X. Zhang
Phys. Rev. Lett. 118, 053001 (2017), arXiv:1605.02143.

“Investigation of two-frequency Paul traps for antihydrogen production”
N. Leefer, K. Krimmel, W. Bertsche, D. Budker, J. Fajans, R. Folman, H. Häffner, F. Schmidt-Kaler
Hyperfine Interactions 238: 12 (2017), arXiv:1603.09444.

“Cryogenic setup for trapped ion quantum computing”
M.F. Brandl, M.W. van Mourik, L. Postler, A. Nolf, K. Lakhmanskiy, R.R. Paiva, S. Möller, N. Daniilidis, H Häffner, V. Kaushal, T. Ruster, C. Warschburger, H. Kaufmann, U.G. Poschinger, F. Schmidt-Kaler, P. Schindler, T. Monz, R. Blatt
Rev. Sci. Instrum. 87, 113103 (2016), arXiv:1607.04980.

“Implications of surface noise for the motional coherence of trapped ions”
I. Talukdar, D.J Gorman, N. Daniilidis, P. Schindler, S. Ebadi, H. Kaufmann, T. Zhang, H. Häffner
Phys. Rev. A 93, 043415 (2016), arXiv:1511.04819.

“Strongly enhanced effects of Lorentz symmetry violation in entangled Yb+ ions”
P. Dzuba, V. V. Flambaum, M. S. Safronova, S. G. Porsev, T. Pruttivarasin, M. A. Hohensee, H. Häffner
Nature Physics 12, 465 - 468 (2016), arXiv:1507.06048.

“Polarization of electric field noise near metallic surfaces”
P. Schindler, D.J Gorman, N. Daniilidis, H. Häffner
Phys. Rev. A 92, 013414 (2015), arXiv:1505.01237.

“Design of a Surface Trap for Freely Rotating Ion Ring Crystals”
P.J. Wang, T. Li, C. Noel, A. Chuang, X. Zhang, H. Häffner
J. Phys. B 48, 205002 (2015), arXiv:1412.3551.

“Michelson-Morley analogue for electrons using trapped ions to test Lorentz symmetry”
T. Pruttivarasin, M. Ramm, S. G. Porsev, I. I. Tupitsyn, M. Safronova, M. A. Hohensee, H. Häffner
Nature 517, 592 (2015), News & Views, podcast, arXiv:1412.2194.

“Resistive and sympathetic cooling of highly-charged-ion clouds in a Penning trap”
M. Vogel, H. Häffner, K. Hermanspahn, S. Stahl, J. Steinmann, W. Quint
Phys. Rev. A 90, 043412 (2014).

“Two-mode coupling in a single-ion oscillator via parametric resonance”
D.J Gorman, P. Schindler, S. Selvarajan, N. Daniilidis, and H. Häffner
Phys. Rev. A 89, 062332 (2014), arXiv:1405.5571.

“Coherent all-optical control of ultracold atoms arrays in permanent magnetic traps”
A. Abdelrahman, T. Mukai, H. Häffner, and T. Byrnes
Optics Express 22, 3501 (2014).

“Observing a Quantum Phase Transition by Measuring a Single Spin”
M. Gessner, M. Ramm, H. Häffner, A. Buchleitner, and H.-P. Breuer
Europhysics Letters 107, 4005 (2014), arXiv:1403.4066.

“Direct spectroscopy of the 2S1/2-2P1/2 and 2D3/2-2P1/2 transitions and observation of micromotion modulated spectra in trapped Ca+”
T. Pruttivarasin, M. Ramm, and H. Häffner.
J. Phys. B 47, 135002 (2014), arXiv:1312.7617.

“Energy Transport in Trapped Ion Chains”
M. Ramm, T. Pruttivarasin, and H. Häffner.
New J. Phys. 16, 063062 (2014), arXiv:1312.5786. Higlighted in IOP select .

“Nonlinear spectroscopy of controllable many-body quantum systems”
M. Gessner, F. Schlawin, H. Häffner, S. Mukamel, and A. Buchleitner.
New J. Phys. 16, 092001 (2014), arXiv:1312.3365. Selected for Highlights of 2014 collection - New Journal of Physics.

“Local Detection of Quantum Correlations with a Single Trapped Ion”
M. Gessner, M. Ramm, T. Pruttivarasin, A. Buchleitner, H.-P. Breuer, and H. Häffner.
Nature Phys. 10, 105-109 (2014), arXiv:1311.4489.

“Probing surface electric field noise with a single ion”
N. Daniilidis, S. Gerber, G. Bolloten, M. Ramm, A. Ransford, E. Ulin-Avila, I. Talukdar, and H. Häffner.
Phys. Rev. B 89, 245435 (2014), arXiv:1307.7194.

“Precision Measurement Method for Branching Fractions of Excited P1/2 States Applied to 40Ca+”
M. Ramm, T. Pruttivarasin, M. Kokish, I. Talukdar, and H. Häffner.
Phys. Rev. Lett. 111, 023004 (2013), arXiv:1305.0858.

“Quantum information processing with trapped electrons and superconducting electronics”
N. Daniilidis, D.J Gorman, L. Tian, and H. Häffner.
New J. Phys. 15, 073017 (2013), arXiv:1304.4710.

“Quantum Interfaces Between Atomic and Solid-State Systems”
N. Daniilidis and H. Häffner.
Annual Reviews Condensed Matter Physics 4, 83-112 (2013), Download.

“Collective Quantum Jumps of Rydberg Atoms”
T.E. Lee, H. Häffner, and M.C. Cross.
Phys. Rev. Lett. 108, 023602 (2012), arXiv:1109.6506. Selected for a Physics Viewpoint.

“Electric field compensation and sensing with a single ion in a planar trap”
S. Narayanan, N. Daniilidis, S. A. Möller, R. Clark, F. Ziesel, K. Singer, F. Schmidt-Kaler, and H. Häffner.
J. Appl. Phys. 110, 114909 (2011), arXiv:1106.2730.

“Transport of charged particles by adjusting rf voltage amplitudes”
T. Karin, I. Le Bras, A. Kehlberger, K. Singer, N. Daniilidis, and H. Häffner.
Appl. Phys. B 106, 117 (2012), arXiv:1011.6116.

“Antiferromagnetic phase transition in a nonequilibrium lattice of Rydberg atoms”
T.E. Lee, H. Häffner, and M.C. Cross.
Phys. Rev. A 84, 031402(R) (2011), arXiv:1104.0908. Selected for a Physics Viewpoint.

“All that is gold does not glitter”
N. Daniilidis and H. Häffner.
Physics 4, 66 (2011).

“Trapped ions in optical lattices for probing oscillator chain models”
T. Pruttivarasin, M. Ramm, I. Talukdar, A. Kreuter, and H. Häffner.
New J. Phys. 13, 075012 (2011), arXiv:1104.0451. Selected for Highlights of 2011 collection - New Journal of Physics.

“Fabrication and heating rate study of microscopic surface electrode ion traps”
N. Daniilidis, S. Narayanan, S.A. Möller, R. Clark, T.E. Lee, P.J. Leek, A. Wallraff, St. Schulz, F. Schmidt-Kaler, and H. Häffner.
New J. Phys. 13, 013032 (2011), arXiv:1009.2834.

“Frustrated trio mimicked”
H. Häffner.
Nature 465, 555, (2010).

Introductory article on “Quantum computing with trapped ions”
H. Häffner.
Journal of the Indian Institute of Science 89, No. 3 (2009) in ‘Quantum Computation-Current trends and implementations’, Eds. V. Natarajan, and A. Kumar. Download.

“Wiring up trapped ions to study aspects of quantum information”
N. Daniilidis, T. Lee, R. Clark, S. Narayanan, and H. Häffner.
J. Phys. B 42, 144012 (2009), arXiv:0903.3834.

“Optimal control of entangling operations for trapped-ion quantum computing”
V. Nebendahl, H. Häffner, and C. F. Roos.
Phys. Rev. A 79, 012312 (2009), arXiv:0809.1414.

Review on “Quantum computing with trapped ions”
H. Häffner, C. F. Roos, and R. Blatt.
Physics Reports 469, 155 (2008), arXiv:0809.4368.

PhD Theses

“Creating and Destroying Rotational Quantum Coherence in a Trapped-Ion Coulomb Crystal Rotor”
N. Glikin (2023). Download.

“Quantum metrology with trapped ions”
J. Broz (2023). Download.

“Efficient and trusted operation of quantum computers and quantum simulators”
R. Shaffer (2022). Download.

“Electric-field noise scaling and wire-mediated ion-ion energy exchange in a novel elevator surface trap”
D. An (2021). Download.

“Treatments of a Surface Ion Trap: A Study of Electric-Field Noise near a Contaminated Metal Surface”
M. Berlin-Udi (2020). Download.

“High temperature studies of electric-field noise in a surface ion trap”
C. Noel (2019). Download.

“Implementation of a Rotationally Symmetric Ring Ion Trap and Coherent Control of Rotational States”
E. Urban (2019). Download.

“Establishing tools to optimize surface traps for wiring up trapped ions”
S. Selvarajan (2017). Download.

“Noise sensing and quantum simulation with trapped atomic ions”
D. Gorman (2017). Download.

“How to couple trapped ions to superconducting resonators: towards hybrid quantum devices”
S. Moeller (2016). Download.

“Spectroscopy, fundamental symmetry tests and quantum simulation with trapped ions”
T. Pruttivarasin (2014). Download.

“Quantum Correlations and Energy Transport in Trapped Ions”
M. Ramm (2014). Download.

Masters Theses

“Electrostatic Control and Transport of Ions on a Planar Trap for Quantum Information Processing”
G. Littich (2011). Download.