arXiv subjects

Vincent M. Klinkhamer

Publications and source records attributed to Vincent M. Klinkhamer.

3 recordsLinked to original sources

arXiv2019

Experimental Characterization of Two-Particle Entanglement through Position and Momentum Correlations

Quantum simulation is a rapidly advancing tool to gain insight into complex quantum states and their dynamics. Trapped ion systems have pioneered deterministic state preparation and comprehensive state characterization, operating on localized and thus distinguishable particles. With ultracold atom experiments, one can prepare large samples of delocalized particles, but the same level of characterization has not yet been achieved. Here, we present a method to measure the positions and momenta of individual particles to obtain correlations and coherences. We demonstrate this with deterministically prepared samples of two interacting ultracold fermions in a coupled double well. As a first application, we use our technique to certify and quantify different types of entanglement.

cond-mat.quant-gas↗

arXiv2018

Spin-resolved single-atom imaging of $^6$Li in free space

We present a versatile imaging scheme for fermionic $^6$Li atoms with single-particle sensitivity. Our method works for freely propagating particles and completely eliminates the need for confining potentials during the imaging process. We illuminate individual atoms in free space with resonant light and collect their fluorescence on an electron-multiplying CCD camera using a high-numerical-aperture imaging system. We detect approximately \num{20} photons per atom during an exposure of 20 $μ$s and identify individual atoms with a fidelity of $99.4\pm0.3$ % . By addressing different optical transitions during two exposures in rapid succession, we additionally resolve the hyperfine spin state of each particle. The position uncertainty of the imaging scheme is 4.0 $μ$m, given by the diffusive motion of the particles during the imaging pulse. The absence of confining potentials enables readout procedures, such as the measurement of single-particle momenta in time of flight, which we demonstrate here. Our imaging scheme is technically simple and easily adapted to other atomic species.

cond-mat.quant-gas↗

arXiv2015

Two Fermions in a double well: Exploring a fundamental building block of the Hubbard model

We have prepared two ultracold fermionic atoms in an isolated double-well potential and obtained full control over the quantum state of this system. In particular, we can independently control the interaction strength between the particles, their tunneling rate between the wells and the tilt of the potential. By introducing repulsive (attractive) interparticle interactions we have realized the two-particle analog of a Mott-insulating (charge-density-wave) state. We have also spectroscopically observed how second-order tunneling affects the energy of the system. This work realizes the first step of a bottom-up approach to deterministically create a single-site addressable realization of a ground-state Fermi-Hubbard system.

cond-mat.quant-gas↗