This paper describes the experimental creation and imaging of vortices in a two-component Bose-Einstein condensate (BEC). The vortices were created through a coherent process involving the spatial and temporal control of interconversion between the two components. The vortex state was confirmed to possess angular momentum using an interference technique that mapped the phase of the vortex state. The researchers created vortices in either of the two components and observed differences in their dynamics and stability. The concept of a vortex is central to understanding superfluidity. In a superfluid, a vortex is a topological feature where the phase undergoes a 2π winding. The experimental realization of a dilute atomic BEC has led to significant theoretical interest in the formation and behavior of vortices in BEC. This paper presents the experimental realization and imaging of a vortex in BEC. The researchers used a method proposed by Williams and Holland to create vortices in a two-component BEC. An interference technique was used to obtain phase images of the vortex state and confirm the 2π phase winding required by the quantization condition. Vortices in superfluid helium are created by rotating a bucket of helium through the superfluid transition. However, this does not work for BEC because it is formed in a harmonic magnetic trap. When the condensate first forms, it occupies a tiny cross-sectional area at the center of the trap and is too small to support a vortex. Eventually, the condensate grows to sufficient size that it can support vortices. The researchers avoided uncertainties by creating vortices using a coherent process that directly forms the desired vortex wave function via transitions between two internal spin states of 87Rb. The two spin states, |1> and |2>, are separated by the ground-state hyperfine splitting and can be simultaneously confined in identical and fully overlapping magnetic trap potentials. The researchers used a two-photon microwave field to induce transitions between the states. The vortex state is an axially symmetric ring with a 2π phase winding around the vortex core where the local density is zero. To create a wave function with this spatial symmetry, the laser beam is rotated around the initial condensate. The desired spatial phase dependence is obtained by detuning the microwave frequency from the transition and rotating the laser beam at the appropriate frequency ω to make the coupling resonant. The center of the condensate feels no time-varying change, while regions near the circumference of the condensate feel a near-sinusoidal variation, with a phase delay equal to the azimuthal angle θ around the circumference of the cloud. The researchers used the overlap of the |1> and |2> fluids to image the phase profile of the vortex state via the interconversion interference technique. The application of a resonant π/2 microwave pulse transforms the original two-fluid density distribution into a distribution that reflects the local phase difference, a "phase interferogramThis paper describes the experimental creation and imaging of vortices in a two-component Bose-Einstein condensate (BEC). The vortices were created through a coherent process involving the spatial and temporal control of interconversion between the two components. The vortex state was confirmed to possess angular momentum using an interference technique that mapped the phase of the vortex state. The researchers created vortices in either of the two components and observed differences in their dynamics and stability. The concept of a vortex is central to understanding superfluidity. In a superfluid, a vortex is a topological feature where the phase undergoes a 2π winding. The experimental realization of a dilute atomic BEC has led to significant theoretical interest in the formation and behavior of vortices in BEC. This paper presents the experimental realization and imaging of a vortex in BEC. The researchers used a method proposed by Williams and Holland to create vortices in a two-component BEC. An interference technique was used to obtain phase images of the vortex state and confirm the 2π phase winding required by the quantization condition. Vortices in superfluid helium are created by rotating a bucket of helium through the superfluid transition. However, this does not work for BEC because it is formed in a harmonic magnetic trap. When the condensate first forms, it occupies a tiny cross-sectional area at the center of the trap and is too small to support a vortex. Eventually, the condensate grows to sufficient size that it can support vortices. The researchers avoided uncertainties by creating vortices using a coherent process that directly forms the desired vortex wave function via transitions between two internal spin states of 87Rb. The two spin states, |1> and |2>, are separated by the ground-state hyperfine splitting and can be simultaneously confined in identical and fully overlapping magnetic trap potentials. The researchers used a two-photon microwave field to induce transitions between the states. The vortex state is an axially symmetric ring with a 2π phase winding around the vortex core where the local density is zero. To create a wave function with this spatial symmetry, the laser beam is rotated around the initial condensate. The desired spatial phase dependence is obtained by detuning the microwave frequency from the transition and rotating the laser beam at the appropriate frequency ω to make the coupling resonant. The center of the condensate feels no time-varying change, while regions near the circumference of the condensate feel a near-sinusoidal variation, with a phase delay equal to the azimuthal angle θ around the circumference of the cloud. The researchers used the overlap of the |1> and |2> fluids to image the phase profile of the vortex state via the interconversion interference technique. The application of a resonant π/2 microwave pulse transforms the original two-fluid density distribution into a distribution that reflects the local phase difference, a "phase interferogram