39 citations · 209 across the 14 of their papers we have counts for
14 papers
Non-Gaussian generalized two-mode squeezing: applications to two-ensemble spin squeezing and beyond
Mikhail Mamaev, Martin Koppenhöfer, Andrew Pocklington +1
Bosonic two-mode squeezed states are paradigmatic entangled Gaussian states that have wide utility in quantum information and metrology. Here, we show that the basic structure of t…
Revisiting the impact of dissipation on time-reversed one-axis-twist quantum-sensing protocols
Martin Koppenhöfer, A. A. Clerk
Spin squeezing can increase the sensitivity of interferometric measurements of small signals in large spin ensembles beyond the standard quantum limit. In many practical settings,…
Squeezed superradiance enables robust entanglement-enhanced metrology even with highly imperfect readout
Martin Koppenhöfer, Peter Groszkowski, A. A. Clerk
Quantum metrology protocols using entangled states of large spin ensembles attempt to achieve measurement sensitivities surpassing the standard quantum limit (SQL), but in many cas…
Geometric Phase in Quantum Synchronization
Aaron Daniel, Christoph Bruder, Martin Koppenhöfer
We consider a quantum limit-cycle oscillator implemented in a spin system whose quantization axis is slowly rotated. Using a kinematic approach to define geometric phases in nonuni…
Single-Spin Readout and Quantum Sensing using Optomechanically Induced Transparency
Martin Koppenhöfer, Carl Padgett, Jeffrey V. Cady +4
Solid-state spin defects are promising quantum sensors for a large variety of sensing targets. Some of these defects couple appreciably to strain in the host material. We propose t…
Half-integer vs. integer effects in quantum synchronization of spin systems
Ryan Tan, Christoph Bruder, Martin Koppenhöfer
We study the quantum synchronization of a single spin driven by an external semiclassical signal for spin numbers larger than , the smallest system to host a quantum self-su…
Preparation of Metrological States in Dipolar-Interacting Spin Systems
Tian-Xing Zheng, Anran Li, Jude Rosen +7
Spin systems are an attractive candidate for quantum-enhanced metrology. Here we develop a variational method to generate metrological states in small dipolar-interacting ensembles…
Dissipative superradiant spin amplifier for enhanced quantum sensing
Martin Koppenhöfer, Peter Groszkowski, Hoi-Kwan Lau +1
Quantum metrology protocols exploiting ensembles of two-level systems and Ramsey-style measurements are ubiquitous. However, in many cases excess readout noise severely degrade…
Reservoir-engineered spin squeezing: macroscopic even-odd effects and hybrid-systems implementations
Peter Groszkowski, Martin Koppenhöfer, Hoi-Kwan Lau +1
We revisit the dissipative approach to producing and stabilizing spin-squeezed states of an ensemble of two-level systems, providing a detailed analysis of two surprising yet g…
Creating photon-number squeezed strong microwave fields by a Cooper-pair injection laser
Martin Koppenhöfer, Juha Leppäkangas, Michael Marthaler
The use of artificial atoms as an active lasing medium opens a way to construct novel sources of nonclassical radiation. An example is the creation of photon-number squeezed light.…
Superconducting quantum metamaterials as active lasing medium: Effects of disorder
Martin Koppenhöfer, Michael Marthaler, Gerd Schön
A metamaterial formed by superconducting circuits or quantum dots can serve as active lasing medium when coupled to a microwave resonator. For these artificial atoms, in contrast t…
Lasing at arbitrary frequencies with atoms with broken inversion symmetry and an engineered electromagnetic environment
Michael Marthaler, Martin Koppenhöfer, Karolina Słowik +1
With the purpose to devise a novel lasing scheme, we consider a two level system with both a transversal and longitudinal coupling to the electromagnetic field. If the longitudinal…
Creation of a squeezed photon distribution using artificial atoms with broken inversion symmetry
Martin Koppenhöfer, Michael Marthaler
We consider a two level system with both a transversal and a longitudinal coupling to the electromagnetic field of a resonator. Using a polaron transformation, this Hamiltonian can…
Lorentz angle measurements in irradiated silicon detectors between 77 K and 300 K
W. de Boer, V. Bartsch, J. Bol +7
Future experiments are using silicon detectors in a high radiation environment and in high magnetic fields. The radiation tolerance of silicon improves by cooling it to temperature…