Systems consisting of few interacting fermions are the building blocks matter, with atoms and nuclei being most prominent examples. We have created a few-body quantum system complete control over its state using ultracold fermionic in an optical dipole trap. Ground-state systems 1 to 10 particles prepared fidelities ∼90%. can tune interparticle interactions arbitrary values Feshbach resonance observed interaction-induced energy shift for pair repulsively atoms. This work is expected enable...

Knowing when a physical system has reached sufficient size for its macroscopic properties to be well described by many-body theory is difficult. We investigate the crossover from few physics studying quasi one-dimensional systems of ultracold atoms consisting single impurity interacting with an increasing number identical fermions. measure interaction energy such as function majority different strengths interparticle interaction. As we increase one observe fast convergence normalized towards...

In this work we study a system of two distinguishable fermions in 1D harmonic potential. This has the exceptional property that there is an analytic solution for arbitrary values interparticle interaction. We tune interaction strength via magnetic offset field and compare measured properties to theoretical prediction. At point where diverges, energy square wave function particles are same as identical fermions. referred fermionization. have observed phenomenon by directly comparing with...

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 interaction strength between particles, their tunneling rate wells tilt potential. By introducing repulsive (attractive) interparticle interactions realized two-particle analog a Mott-insulating (charge-density-wave) state. also spectroscopically observed how second-order affects energy This work realizes...

We perform radio-frequency dissociation spectroscopy of weakly bound 6Li2 Feshbach molecules using low-density samples about 30 in an optical dipole trap. Combined with a high magnetic field stability, this allows us to resolve the discrete trap levels spectra. This novel technique binding energy be determined unprecedented precision. use these measurements as input for fit 6Li scattering potential coupled-channel calculations. From new potential, we determine pole positions broad resonances...

We report on the deterministic preparation of antiferromagnetic Heisenberg spin chains consisting up to four fermionic atoms in a one-dimensional trap. These are stabilized by strong repulsive interactions between two components without need for an external periodic potential. independently characterize configuration measuring orientation outermost particle trap and projecting spatial wave function one component single-particle levels. Our results good agreement with spin-chain model...

We use the resonant dipole-dipole interaction between Rydberg atoms and a periodic external microwave field to engineer XXZ spin Hamiltonians with tunable anisotropies. The are placed in 1D 2D arrays of optical tweezers, allowing us study iconic situations physics, such as implementation Heisenberg model square arrays, transport 1D. first benchmark Hamiltonian engineering for two atoms, then demonstrate freezing magnetization on an initially magnetized array. Finally, we explore dynamics...

We study quasi-one-dimensional few-particle systems consisting of one to six ultracold fermionic atoms in two different spin states with attractive interactions. probe the system by deforming trapping potential and observing tunneling particles out trap. For even particle numbers, we observe a behavior that deviates from uncorrelated single-particle indicating existence pair correlations system. From time scales, infer differences interaction energies number particles, which show strong...

The quantum-mechanical three-body problem is one of the fundamental challenges few-body physics. When two-body interactions become resonant, an infinite series universal bound states predicted to occur, whose properties are determined by strength interactions. We report on association and direct observation a trimer state consisting three distinguishable fermions using radio-frequency (RF) spectroscopy. measurements its binding energy consistent with theoretical predictions which include...

The condensation of fermion pairs lies at the heart superfluidity. However, for strongly correlated systems with reduced dimensionality mechanisms pairing and are still not fully understood. In our experiment we use ultracold atoms as a generic model system to study phase transition from normal condensed in interacting quasi-two-dimensional Fermi gas. Using novel method, obtain situ pair momentum distribution observe emergence low-momentum condensate low temperatures. By tuning temperature...

We experimentally investigate the first-order correlation function of a trapped Fermi gas in two-dimensional BEC-BCS crossover. observe transition to low-temperature superfluid phase with algebraically decaying correlations. show that spatial coherence entire system can be characterized by single temperature-dependent exponent. find exponent at constant over wide range interaction strengths across This suggests transitions both bosonic regime and strongly interacting crossover are...

We report the experimental measurement of equation state a two-dimensional Fermi gas with attractive s-wave interactions throughout crossover from weakly coupled to Bose tightly bound dimers as interaction strength is varied. demonstrate that lead renormalization density by several orders magnitude. compare our data near ground and at finite temperature predictions for both fermions bosons Quantum Monte Carlo simulations Luttinger-Ward theory. Our results serve input investigations...

We present a versatile imaging scheme for fermionic Li6 atoms with single-particle sensitivity. Our method works freely propagating particles and completely eliminates the need confining potentials during process. illuminate individual in free space resonant light collect their fluorescence on an electron-multiplying CCD camera using high-numerical-aperture system. detect approximately 20 photons per atom exposure of 20μs identify fidelity (99.4±0.3)%. By addressing different optical...

Controlling interactions is the key element for quantum engineering of many-body systems. Using time-periodic driving, a naturally given Hamiltonian closed system can be transformed into an effective target that exhibits vastly different dynamics. We demonstrate such Floquet with spins represented by Rydberg states in ultracold atomic gas. By applying sequence spin manipulations, we change symmetry properties Heisenberg XYZ Hamiltonian. As consequence, relaxation behavior total drastically...

Understanding the dynamics of strongly interacting disordered quantum systems is one most challenging problems in modern science, due to features such as breakdown thermalization and emergence glassy phases matter. We report on observation anomalous relaxation an isolated XXZ spin system realized by ultracold gas atoms initially prepared a superposition two-different Rydberg states. The total magnetization found exhibit sub-exponential analogous classical dynamics, but case this originates...

Ultracold gases of three distinguishable particles with large scattering lengths are expected to show rich few-body physics related the Efimov effect. We have created different mixtures ultracold 6Li atoms and weakly bound 6Li2 dimers consisting in hyperfine states studied their inelastic decay via atom-dimer collisions. found resonant enhancement due crossing Efimov-like trimer continuum one mixture as well minima another mixture, which we interpret a suppression exchange reactions type...

We show that the recently measured magnetic field dependence of three-body loss in a three-component mixture ultracold $^{6}\text{L}\text{i}$ atoms [T. B. Ottenstein et al., Phys. Rev. Lett. 101, 203202 (2008); J. H. Huckans 102, 165302 (2009)] can be explained by presence universal trimer state. Previous work suggested state as probable explanation, yet it failed to get good agreement between theory and experiment over whole range fields. For our description we adapt Braaten Hammer [Phys....

We perform a theoretical and experimental study of system two ultracold atoms with tunable interaction in an elongated trapping potential. show that the coupling center-of-mass relative motion due to anharmonicity potential leads coherent state unbound atom pair molecule center mass excitation. By performing experiment exactly particles we exclude three-body losses can therefore directly observe formation. find quantitative agreement between our theory inelastic confinement-induced...

We demonstrate and characterize an experimental technique to directly image the momentum distribution of a strongly interacting two-dimensional quantum gas with high resolution. apply principles Fourier optics investigate three main operations on expanding gas: focusing, collimation magnification. focus in radial plane using harmonic confining potential thus gain access distribution. pulse different stop rapid axial expansion which allows us Additionally, we propose method magnify mapped...

We observe many-body pairing in a two-dimensional gas of ultracold fermionic atoms at temperatures far above the critical temperature for superfluidity. For this, we use spatially resolved radio-frequency spectroscopy to measure energies spanning wide range and interaction strengths. In strongly interacting regime where scattering length between fermions is on same order as inter-particle spacing, energy normal phase significantly exceeds intrinsic two-body binding system shows clear...

An important step towards a comprehensive understanding of far-from-equilibrium dynamics quantum many-body systems is the identification unifying features that are independent microscopic details system. We experimentally observe such robust in magnetization relaxation disordered Heisenberg XX, XXZ, and Ising Hamiltonians. realize these spin models with tunable anisotropy parameter power-law interactions an ensemble Rydberg atoms by encoding suitable state combinations. consistently...

We study the out-of-equilibrium dynamics in quantum Ising model with power-law interactions and positional disorder. For arbitrary dimension $d$ interaction range $\alpha \geq d$ we analytically find a stretched exponential decay of global magnetization ensemble-averaged single-spin purity stretch-power $\beta = d/\alpha$ thermodynamic limit. Numerically, confirm that glassy behavior persists for finite system sizes sufficiently strong identify dephasing between disordered coherent pairs as...

We present combined measurements of the spatially-resolved optical spectrum and total excited-atom number in an ultracold gas three-level atoms under electromagnetically induced transparency conditions involving high-lying Rydberg states. The observed transmission a weak probe laser at center coupling region exhibits double peaked as function detuning, whilst atom shows comparatively narrow single resonance. By imaging transmitted light onto charge-coupled-device camera, we record hundreds...

Time reversal in a macroscopic system is contradicting daily experience. It practically impossible to restore shattered cup its original state by just time reversing the microscopic dynamics that led breakage. Yet, with precise control capabilities provided modern quantum technology, unitary evolution of can be reversed time. Here, we implement time-reversal protocol dipolar interacting, isolated many-body spin represented Rydberg states an atomic gas. By changing encoding spin, flip sign...