Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:0903.3552 · Physical Review A

Cavity QED in a molecular ion trap

David Schuster, Lev S. Bishop, Isaac L. Chuang, D. DeMille, R. J. Schoelkopf

Published Jan 19, 2011• 61 citations
arXivHTMLPDF

Abstract

We propose a class of experiments using rotational states of dipolar molecular ions trapped near an on-chip superconducting microwave cavity. Molecular ions have several advantages over neutral molecules for such cavity quantum electrodynamics experiments. In particular, ions can be loaded easily into deep rf traps and are held independent of their internal state. An analysis of the detection efficiency for, and coherence properties of, the molecular ions is presented. We discuss approaches for manipulating quantum information and performing high-resolution rotational spectroscopy using this system.

DOI
10.1103/physreva.83.012311

Related papers

Quantum logic control and spectroscopy of a single molecular ion

Alejandra Collopy, David R. Leibrandt, Dietrich G. Leibfried +1 more

Quantum logic enables state preparation, readout and spectroscopy of otherwise difficult-to-study ions. Using the coupled harmonic motion shared between co-trapped ions, information can be transferred from the "spectroscopy" ion to the easily manipulated "logic" ion. With this technique we perform high-resolution terahertz-scale rotational spectroscopy of a single CaH+ molecular ion in pure states by leveraging a Ca+ ion as our logic ion. Entangled states between a CaH+ and a Ca+ have also been demonstrated, making molecular ions possible components of hybrid systems for quantum information processing. Because all our laser operations on the molecule are driving stimulated Raman transitions with high detuning, the technique promises to be generalizable to a wide variety of molecular ion species. Additionally, we study the systematic effects of the trap RF electric field on molecular levels and use it to obtain a measurement of the dipole moment of the charged molecule.

Optical and Quantum Sensing and Precision Metrology•Mar 4, 2021•0 citations

Polar molecules near superconducting resonators: a coherent, all-electrical, molecule-mesoscopic interface

Axel André, David P. DeMille, John M. Doyle +5 more

The challenge of building a scalable quantum processor requires consolidation of the conflicting requirements of achieving coherent control and preservation of quantum coherence in a large scale quantum system. Moreover, the system should be compatible with miniaturization and integration of quantum circuits. Mesoscopic solid state systems such as superconducting islands and quantum dots feature robust control techniques using local electrical signals and self-evident scaling based on advances in fabrication; however, in general the quantum states of solid state devices tend to decohere rapidly. In contrast, quantum optical systems based on trapped ions and neutral atoms exhibit dramatically better coherence properties, while miniaturization of atomic and molecular systems, and their integration with mesoscopic electrical circuits, remains an important challenge. Below we describe methods for the integration of a single particle system -- an isolated polar molecule -- with mesoscopic solid state devices in a way that produces robust, coherent, quantum-level control. The methods described include the trapping, cooling, detection, coherent manipulation and quantum coupling of isolated polar molecules at sub-micron dimensions near cryogenic stripline microwave resonators. We show that electrostatically trapped polar molecules can exhibit strong confinement and fast, purely electrical gate control. Furthermore, the effect of electrical noise sources, a key issue in quantum information processing, can be suppressed to very low levels via appropriate preparation and manipulation of the polar molecules. Our setup provides a scalable cavity QED-type quantum computer architecture, where entanglement of distant qubits stored in long-lived rotational molecular states is achieved via exchange of microwave photons.

arXiv:quant-ph/0605201•May 23, 2006•5 citations

State-selective coherent motional excitation as a new approach for the manipulation, spectroscopy and state-to-state chemistry of single molecular ions

Ziv Meir, Gregor Hegi, Kaveh Najafian +2 more

We present theoretical and experimental progress towards a new approach for the precision spectroscopy, coherent manipulation and state-to-state chemistry of single isolated molecular ions in the gas phase. Our method uses a molecular beam for creating packets of rotationally cold neutrals from which a single molecule is state-selectively ionized and trapped inside a radiofrequency ion trap. In addition to the molecular ion, a single co-trapped atomic ion is used to cool the molecular external degrees of freedom to the ground state of the trap and to detect the molecular state using state-selective coherent motional excitation from a modulated optical-dipole force acting on the molecule. We present a detailed discussion and theoretical characterization of the present approach. We simulate the molecular signal experimentally using a single atomic ion, indicating that different rovibronic molecular states can be resolved and individually detected with our method. The present approach for the coherent control and non-destructive detection of the quantum state of a single molecular ion opens up new perspectives for precision spectroscopies relevant for, e.g., tests of fundamental physical theories and the development of new types of clocks based on molecular vibrational transitions. It will also enable the observation and control of chemical reactions of single particles on the quantum level. While focusing on N2+ as a prototypical example in the present work, our method is applicable to a wide range of diatomic and polyatomic molecules.

arXiv:1909.10292•Faraday Discussions•Dec 11, 2018•17 citations

A cryogenic ion trap for quantum-logic spectroscopy of single molecular ions

Julian Schmidt, Dalton W. Chaffee, Yu Liu +3 more

Expanding the toolbox available for the control of individual atoms or ions to single molecules has many promising applications. Using quantum-logic spectroscopy, our group has demonstrated preparation, coherent manipulation, and nondestructive detection of rotational states of CaH+ molecular ions, as well as entangled states relevant for quantum information processing. We are currently building a new cryogenic experimental setup which features a molecular beam with interchangeable gas sources to overcome limitations in the existing experimental setup. With this setup, we plan to improve control over small molecules such as CaH+ and explore quantum state control of larger molecules.

Optical and Quantum Sensing and Precision Metrology II•Mar 9, 2022•0 citations

Quantum state preparation and control of single molecular ions

Dietrich G. Leibfried

Abstract. Preparing molecules at rest and in a highly pure quantum state is a long standing dream in chemistry and physics, so far achieved only for a select set of molecules in dedicated experimental setups. Here, a quantum-limited combination of mass spectrometry and Raman spectroscopy is proposed that should be applicable to a wide range of molecular ions. Excitation of electrons in the molecule followed by uncontrolled decay and branching into several lower energy states is avoided. Instead, the molecule is always confined to rotational states within the electronic and vibrational ground-state manifold, while a co-trapped atomic ion provides efficient entropy removal and allows for extraction of information on the molecule. The outlined techniques might enable preparation, manipulation and measurement of a large multitude of molecular ion species with the same instrument, with applications including, but not limited to, precise determination of molecular properties and fundamental tests of physics. 1.

•Aug 17, 2016•33 citations

Spin resonance with trapped ions

Ch. Wunderlich, Ch. Balzer, Th. Hannemann +4 more

Am odified ion trap is described where experiments (in particular related to quantum information processing) that usually require optical radiation can be carried out using microwave or radio frequency electromagnetic fields. Instead of applying the usual methods for coherent manipulation of trapped ions, a string of ions in such a modified trap can be treated like a molecule in nuclear magnetic resonance experiments taking advantage of spin–spin coupling. The collection of trapped ions can be viewed as an N-qubit molecule with adjustable spin–spin coupling constants. Given N identically prepared quantum mechanical two-level systems (qubits), the optimal strategy to estimate their quantum state requires collective measurements. Using the ground state hyperfine levels of electrodynamically trapped 171 Yb + ,w e hav ei mplemented an adaptive algorithm for state estimation involvin gs equential measurements on arbitrary qubit states.

Journal of Physics B Atomic Molecular and Optical Physics•Feb 24, 2003•13 citations
We propose a class of experiments using rotational states of dipolar molecular ions trapped near an on-chip superconducting microwave cavity. Molecular ions have several advantages over neutral molecules for such cavity quantum electrodynamics experiments. In particular, ions can be loaded easily into deep rf traps and are held independent of their internal state. An analysis of the detection efficiency for, and coherence properties of, the molecular ions is presented. We discuss approaches for manipulating quantum information and performing high-resolution rotational spectroscopy using this system.
Quantum logic enables state preparation, readout and spectroscopy of otherwise difficult-to-study ions. Using the coupled harmonic motion shared between co-trapped ions, information can be transferred from the "spectroscopy" ion to the easily manipulated "logic" ion. With this technique we perform high-resolution terahertz-scale rotational spectroscopy of a single CaH+ molecular ion in pure states by leveraging a Ca+ ion as our logic ion. Entangled states between a CaH+ and a Ca+ have also been demonstrated, making molecular ions possible components of hybrid systems for quantum information processing. Because all our laser operations on the molecule are driving stimulated Raman transitions with high detuning, the technique promises to be generalizable to a wide variety of molecular ion species. Additionally, we study the systematic effects of the trap RF electric field on molecular levels and use it to obtain a measurement of the dipole moment of the charged molecule.
The challenge of building a scalable quantum processor requires consolidation of the conflicting requirements of achieving coherent control and preservation of quantum coherence in a large scale quantum system. Moreover, the system should be compatible with miniaturization and integration of quantum circuits. Mesoscopic solid state systems such as superconducting islands and quantum dots feature robust control techniques using local electrical signals and self-evident scaling based on advances in fabrication; however, in general the quantum states of solid state devices tend to decohere rapidly. In contrast, quantum optical systems based on trapped ions and neutral atoms exhibit dramatically better coherence properties, while miniaturization of atomic and molecular systems, and their integration with mesoscopic electrical circuits, remains an important challenge. Below we describe methods for the integration of a single particle system -- an isolated polar molecule -- with mesoscopic solid state devices in a way that produces robust, coherent, quantum-level control. The methods described include the trapping, cooling, detection, coherent manipulation and quantum coupling of isolated polar molecules at sub-micron dimensions near cryogenic stripline microwave resonators. We show that electrostatically trapped polar molecules can exhibit strong confinement and fast, purely electrical gate control. Furthermore, the effect of electrical noise sources, a key issue in quantum information processing, can be suppressed to very low levels via appropriate preparation and manipulation of the polar molecules. Our setup provides a scalable cavity QED-type quantum computer architecture, where entanglement of distant qubits stored in long-lived rotational molecular states is achieved via exchange of microwave photons.
We present theoretical and experimental progress towards a new approach for the precision spectroscopy, coherent manipulation and state-to-state chemistry of single isolated molecular ions in the gas phase. Our method uses a molecular beam for creating packets of rotationally cold neutrals from which a single molecule is state-selectively ionized and trapped inside a radiofrequency ion trap. In addition to the molecular ion, a single co-trapped atomic ion is used to cool the molecular external degrees of freedom to the ground state of the trap and to detect the molecular state using state-selective coherent motional excitation from a modulated optical-dipole force acting on the molecule. We present a detailed discussion and theoretical characterization of the present approach. We simulate the molecular signal experimentally using a single atomic ion, indicating that different rovibronic molecular states can be resolved and individually detected with our method. The present approach for the coherent control and non-destructive detection of the quantum state of a single molecular ion opens up new perspectives for precision spectroscopies relevant for, e.g., tests of fundamental physical theories and the development of new types of clocks based on molecular vibrational transitions. It will also enable the observation and control of chemical reactions of single particles on the quantum level. While focusing on N2+ as a prototypical example in the present work, our method is applicable to a wide range of diatomic and polyatomic molecules.
Expanding the toolbox available for the control of individual atoms or ions to single molecules has many promising applications. Using quantum-logic spectroscopy, our group has demonstrated preparation, coherent manipulation, and nondestructive detection of rotational states of CaH+ molecular ions, as well as entangled states relevant for quantum information processing. We are currently building a new cryogenic experimental setup which features a molecular beam with interchangeable gas sources to overcome limitations in the existing experimental setup. With this setup, we plan to improve control over small molecules such as CaH+ and explore quantum state control of larger molecules.
Abstract. Preparing molecules at rest and in a highly pure quantum state is a long standing dream in chemistry and physics, so far achieved only for a select set of molecules in dedicated experimental setups. Here, a quantum-limited combination of mass spectrometry and Raman spectroscopy is proposed that should be applicable to a wide range of molecular ions. Excitation of electrons in the molecule followed by uncontrolled decay and branching into several lower energy states is avoided. Instead, the molecule is always confined to rotational states within the electronic and vibrational ground-state manifold, while a co-trapped atomic ion provides efficient entropy removal and allows for extraction of information on the molecule. The outlined techniques might enable preparation, manipulation and measurement of a large multitude of molecular ion species with the same instrument, with applications including, but not limited to, precise determination of molecular properties and fundamental tests of physics. 1.
Am odified ion trap is described where experiments (in particular related to quantum information processing) that usually require optical radiation can be carried out using microwave or radio frequency electromagnetic fields. Instead of applying the usual methods for coherent manipulation of trapped ions, a string of ions in such a modified trap can be treated like a molecule in nuclear magnetic resonance experiments taking advantage of spin–spin coupling. The collection of trapped ions can be viewed as an N-qubit molecule with adjustable spin–spin coupling constants. Given N identically prepared quantum mechanical two-level systems (qubits), the optimal strategy to estimate their quantum state requires collective measurements. Using the ground state hyperfine levels of electrodynamically trapped 171 Yb + ,w e hav ei mplemented an adaptive algorithm for state estimation involvin gs equential measurements on arbitrary qubit states.