A superconducting circuit includes a first component having a first connection point. The first connection point has a first width. The superconducting circuit includes a second component having a second connection point. The second connection point has a second width that is larger than the first width. The superconducting circuit includes a superconducting connector shaped to reduce current crowding. The superconducting connector electrically connects the first connection point and the second connection point. The superconducting connector includes a first taper positioned adjacent the first connection point and having a non-linear shape and a second taper positioned adjacent the second connection point.

A programmable circuit includes a superconducting component arranged in a multi-dimensional array of alternating narrow and wide portions. The programmable circuit further includes a plurality of heat sources, each heat source configured to selectively provide heat to a respective narrow portion sufficient to transition the respective narrow portion from a superconducting state to a non-superconducting state. The programmable circuit further includes a plurality of electrical terminals, each electrical terminal coupled to a respective wide portion of the multi-dimensional array.

This disclosure relates to optical devices for quantum information processing applications. In one example implementation, a semiconductor structure is provided. The semiconductor structure may be embedded with single defects that can be individually addressed. An electric bias and/or one or more optical excitations may be configured to control the single defects in the semiconductor structure to produce single photons for use in quantum information processing. The electric bias and optical excitations are selected and adjusted to control various carrier processes and to reduce environmental charge instability of the single defects to achieve optical emission with wide wavelength tunability and narrow spectral linewidth. Electrically controlled single photon source and other electro-optical devices may be achieved.

A method of fabricating a device, wherein the device comprises a plurality of lengths of material and at least one junction joining two or more of the lengths of material. In a masking phase, a mask is formed on an underlying layer of the device. The mask comprises a plurality of trenches exposing the underlying layer, each trench corresponding to one of the lengths of material. A respective section of two or more of the trenches either (a) narrow down, or (b) are separated by a discontinuity, at a position corresponding to the at least one junction. In a selective area growth phase, material is grown in the set of trenches to form the lengths of material on the underlying layer. The two or more lengths of material are joined at the at least one junction.

An active three-terminal superconducting device having an intersection region at which a hot spot may be controllably formed is described. The intersection region may exhibit current crowding in response to imbalances in current densities applied to channels connected to intersection region. The current crowding may form a hot spot, in which the superconducting device may exhibit a measurable resistance. In some cases, a three-terminal superconducting device may be configured to sense an amount of superconducting current flowing in a channel or loop without having to perturb the superconducting state or amount of current flowing in the channel. A three-terminal superconducting device may be used to read out a number of fluxons stored in a superconducting memory element.

In some embodiments, a method and apparatus, as well as an article, may operate to determine downhole properties based on detected optical signals. An optical detection apparatus can include an optical detector including a superconducting nanowire single photon detector (SNSPD) for detecting light received at an input section of fiber optic cable. The optical detection apparatus can further include a cryogenic cooler configured to maintain the temperature of a light-sensitive region of the SNSPD within a superconducting temperature range of the SNSPD. Downhole properties are measured based on detected optical signals received at the optical detection apparatus. Additional apparatus, systems, and methods are disclosed.

Devices, systems, methods, computer-implemented methods, apparatus, and/or computer program products that can facilitate a suspended Majorana fermion device comprising an ion implant defined nanorod in a semiconducting device are provided. According to an embodiment, a quantum computing device can comprise a Majorana fermion device coupled to an ion implanted region. The quantum computing device can further comprise an encapsulation film coupled to the ion implanted region and a substrate layer. The encapsulation film suspends the Majorana fermion device in the quantum computing device.

A programmable circuit includes a superconducting component arranged in a multi-dimensional array of alternating narrow and wide portions. The programmable circuit further includes a plurality of heat sources, each heat source configured to selectively provide heat to a respective narrow portion sufficient to transition the respective narrow portion from a superconducting state to a non-superconducting state. The programmable circuit further includes a plurality of electrical terminals, each electrical terminal coupled to a respective wide portion of the multi-dimensional array.

An electronic component having an asymmetric impedance is provided. The component includes first, second and third branches that connect at a common node. The component includes a first portion of superconducting material disposed along the first branch and a second portion of superconducting material disposed along the second branch. The component includes a first device disposed along the first branch and configured to transition the second portion of the superconducting material to a non-superconducting state when a current between a first terminal of the first device and a second terminal of the first device exceeds a first threshold value and a second device disposed along the second branch and configured to transition the first portion of the superconducting material to a non-superconducting state when a current between a first terminal of the second device and a second terminal of the second device exceeds a second threshold value.

Materials and methods are disclosed for fabricating superconducting integrated circuits for quantum computing at millikelvin temperatures, comprising both quantum circuits and classical control circuits, which may be located on the same integrated circuit or on different chips of a multi-chip module. The materials may include components that reduce defect densities and increase quantum coherence times. Multilayer fabrication techniques provide low-power and a path to large scale computing systems. An integrated circuit system for quantum computing is provided, comprising: a substrate; a kinetic inductance layer having a kinetic inductance of at least 5 pH/square; a plurality of stacked planarized superconducting layers and intervening insulating layers, formed into a plurality of Josephson junctions having a critical current of less than 100 μA/μm.sup.2; and a resistive layer that remains non-superconducting at a temperature below 1 K, configured to damp the plurality of Josephson junctions.