ForschungTopical Groups
Spin-squeezing and non-classical states

Spin-squeezing and non-classical states

Concepts for the generation, manipulation and applications of squeezed and entangled atomic ensembles.


  • Contribute to CRC DQ-mat TG1
  • Contribute to TG Quantum Sensors for geo. observ. and rel. geodesy, TG Optical Clock Networks, TG Tests of Fundamental Physics
  • Interact with TG Quantum Computing, TG Open many-body quantum systems, TG Tests of Fundamental Physics
  • Develop concepts for the generation, manipulation and detection of spin-squeezed and entangled many-body states
  • Explore methods for their transfer to external degrees of freedom
  • Devise applications for entanglement-enhanced sensitivities in frequency, magnetic field, and inertial sensing
  • Investigate entangled states for tests of fundamental physics: fundamental sources of decoherence and coupling of quantum objects to general relativity


  • Expertise on quantum-enhanced measurements
  • Efficient description of many-body quantum states
  • Magnetic field stabilization
  • Accurate atom counting
  • Dynamical optical potentials


Anders F, Idel A, Feldmann P, Bondarenko D, Loriani S, Lange K et al. Momentum Entanglement for Atom Interferometry. Physical Review Letters. 2021 Okt 1;127(14). 140402. doi.org/10.1103/PhysRevLett.127.140402

Corgier R, Gaaloul N, Smerzi A, Pezzè L. Delta-kick Squeezing. 2021 Mär 19.

Feldmann P, Klempt C, Smerzi A, Santos L, Gessner M. Interferometric Order Parameter for Excited-State Quantum Phase Transitions in Bose-Einstein Condensates. Physical review letters. 2021 Jun 10;126(23). 230602. doi.org/10.1103/PhysRevLett.126.230602

Kaubruegger R, Vasilyev DV, Schulte M, Hammerer K, Zoller P. Quantum Variational Optimization of Ramsey Interferometry and Atomic Clocks. 2021 Feb 10.

Vitagliano G, Fadel M, Apellaniz I, Kleinmann M, Lücke B, Klempt C et al. Detecting Einstein-Podolsky-Rosen steering and bipartite entanglement in split Dicke states. 2021 Apr 12.

Canuel B, Abend S, Amaro-Seoane P, Badaracco F, Beaufils Q, Bertoldi A et al. ELGAR: a European Laboratory for Gravitation and Atom-interferometric Research. Classical and Quantum Gravity. 2020 Okt 28;37(22). 225017. doi.org/10.1088/1361-6382/aba80e

Chabuda K, Dziarmaga J, Osborne TJ, Demkowicz-Dobrzański R. Tensor-network approach for quantum metrology in many-body quantum systems. Nature Communications. 2020 Jan 14;11(1):250. 250. doi.org/10.1038/s41467-019-13735-9

Chu A, Will J, Arlt J, Klempt C, Rey AM. Simulation of XXZ spin models using sideband transitions in trapped bosonic gases. Physical review letters. 2020 Dez 7;125(24). 240504. doi.org/10.1103/PhysRevLett.125.240504

Lisdat C, Klempt C. Quantum engineering for optical clocks. NATURE. 2020 Dez 16;588(7838):397-398. doi.org/10.1038/d41586-020-03510-y

Schulte M, Lisdat C, Schmidt PO, Sterr U, Hammerer K. Prospects and challenges for squeezing-enhanced optical atomic clocks. Nature Communications. 2020 Nov 24;11(1). 5955. doi.org/10.1038/s41467-020-19403-7

Schulte M, Martínez-Lahuerta VJ, Scharnagl MS, Hammerer K. Ramsey interferometry with generalized one-axis twisting echoes. Quantum. 2020 Mai 15;4:268-286. doi.org/10.22331/q-2020-05-15-268

ELGAR. Technologies for the ELGAR large scale atom interferometer array. 2020 Jul 8.

Hüper A, Pür C, Hetzel M, Geng J, Peise J, Kruse I et al. Preparation of mesoscopic atomic ensembles with single-particle resolution. 2019 Dez 11.

Kristensen MA, Christensen MB, Gajdacz M, Iglicki M, Pawłowski K, Klempt C et al. Observation of Atom Number Fluctuations in a Bose-Einstein Condensate. Physical Review Letters. 2019 Apr 26;122(16):163601. 163601. doi.org/10.1103/PhysRevLett.122.163601

Pezzè L, Gessner M, Feldmann P, Klempt C, Santos L, Smerzi A. Heralded Generation of Macroscopic Superposition States in a Spinor Bose-Einstein Condensate. Physical Review Letters. 2019 Dez 27;123(26). 260403. doi.org/10.1103/PhysRevLett.123.260403

Tino GM, Bassi A, Bianco G, Bongs K, Bouyer P, Cacciapuoti L et al. SAGE: A proposal for a space atomic gravity explorer. European Physical Journal D. 2019 Nov 15;73(11). 228. doi.org/10.1140/epjd/e2019-100324-6

Involved QF Members
Members Institution Relevant Expertise
Carsten Klempt, LeaderLUH / DLR-SIQuantum Atom Optics
Andreas HüperLUHA next-generation Raman system for creating momentum-state entanglement
Alexander IdelLUHQuantum Optics with Non-classical States of Matter
Fabian AndersLUHQuantum Optics with Non-classical States of Matter
Bernd MeyerLUHQuantum Optics with Non-classical States of Matter
Cebrail PürLUHQuantum Optics with Non-classical States of Matter
Mareike HetzelLUHQuantum Optics with Non-classical States of Matter
Martin QuensenLUHQuantum Optics with Non-classical States of Matter
Wolfgang ErtmerLUH/DLR-SIUltracold quantum gases and precision metrology
Luis SantosLUHTheory of Dynamics of Manybody Quantum Systems
Luis Peña ArdilaLUHExcited state phase transitions for the generation of entanglement
Polina FeldmannLUHTheory of quantum phase transitions for the generation of entanglement
Ernst M. RaselLUHQuantum sensors
Christian SchubertLUH/DLR-SIAtom interferometry
Dennis SchlippertLUHAtom interferometry
Naceur GaaloulLUHTheory of many-body physics and atom interferometry
Piet O. SchmidtPTB / LUHSqueezing and non-classical states in trapped ions, precision metrology
Christian LisdatPTBFrequency metrology
Klemens HammererLUHTheory of quantum optics, coupling to general relativity