Abstract: In a general aspect, a radio frequency (RF) measurement device includes first and second mode converters, each configured to convert a mode of the RF electromagnetic wave between a first RF waveguide mode and a second RF waveguide mode. The RF measurement device also includes an internal cavity between the first and second mode converters that contains a vapor or a source of the vapor. The vapor includes Ryberg atoms or molecules. The RF measurement device additionally includes an RF waveguide extending between the first and second mode converters and configured to carry the second RF waveguide mode through the internal cavity. In some variations, the RF waveguide includes first and second longitudinal portions disposed on respective, opposite sides of the device and configured to establish a target RF profile in an interaction region of the internal cavity.

Abstract: In a general aspect, a system for measuring radio frequency (RF) electromagnetic waves includes a laser system configured to generate plurality of input optical signals. The system also includes an RF measurement device having first and second mode converters and an internal cavity therebetween. The internal cavity contains a vapor that is configured to produce an output optical signal based on the plurality of input optical signals. The RF measurement device also includes an RF waveguide that extends between the first and second mode converters and is configured to carry the second RF waveguide mode through the internal cavity. The system also includes an optical detector system configured to generate a detector signal in response to receiving the output optical signal. The system additionally includes a signal processing system configured to generate data in response to receiving the detector signal.

Abstract: In a general aspect, a radio frequency (RF) measurement device includes first and second mode converters, each configured to convert a mode of the RF electromagnetic wave between a first RF waveguide mode and a second RF waveguide mode. The RF measurement device also includes an internal cavity between the first and second mode converters that contains a vapor or a source of the vapor. The vapor includes Ryberg atoms or molecules. The RF measurement device additionally includes an RF waveguide extending between the first and second mode converters and configured to establish a circular polarization of the RF electromagnetic wave in the internal cavity.

Abstract: In a general aspect, a vapor cell includes a body defined by a stack of layers that includes electrically conductive layers and electrically insulating layers. The stack of layers are bonded to each other and have first and second end layers at respective opposite ends of the body. The stack of layers also has intermediate layers between the first and second end layers that define an internal cavity of the body. The internal cavity extends through the body between the first and second end layers and includes a vapor or a source of the vapor disposed therein. Adjacent electrically conductive layers are separated by at least one electrically insulating layer. Moreover, each electrically conductive layer defines an electrode of the vapor cell and includes a contact surface on an exterior side of the body. The contact surface defines an electrical contact of the electrode.

Abstract: In a general aspect, a method includes interacting a beam of light with a vapor in a vapor cell. The vapor cell includes a body defined by a stack of layers that includes electrically conductive layers and electrically insulating layers. The stack of layers are bonded to each other and have first and second end layers at respective opposite ends of the body. The stack of layers also has intermediate layers between the first and second end layers that define an internal cavity of the body. A vapor is disposed in the internal cavity. The method includes applying respective voltages to one or more electrodes to alter an electric field in the internal cavity. The method also includes measuring one or both of an ion signal based on charged particles in the vapor and an optical property of the beam of light after interacting with the vapor.