A cascading selective microwave directional amplifier (cascade) includes a set of Josephson devices, each Josephson device in the set having a corresponding operating bandwidth of microwave frequencies. Different operating bandwidths have different corresponding center frequencies. A series coupling is formed between first Josephson device from the set and an n.sup.th Josephson device from the set. The series coupling causes the first Josephson device to amplify a signal of a first frequency from a frequency multiplexed microwave signal (multiplexed signal) in a first signal flow direction through the series coupling and the n.sup.th Josephson device to amplify a signal of an n.sup.th frequency in a second signal flow direction through the series, where the second signal flow direction is opposite of the first signal flow direction.

A cascading selective microwave directional amplifier (cascade) includes a set of Josephson devices, each Josephson device in the set having a corresponding operating bandwidth of microwave frequencies. Different operating bandwidths have different corresponding center frequencies. A series coupling is formed between first Josephson device from the set and an n.sup.th Josephson device from the set. The series coupling causes the first Josephson device to amplify a signal of a first frequency from a frequency multiplexed microwave signal (multiplexed signal) in a first signal flow direction through the series coupling and the n.sup.th Josephson device to amplify a signal of an n.sup.th frequency in a second signal flow direction through the series, where the second signal flow direction is opposite of the first signal flow direction.

One example includes a parametric amplifier system. The system includes an input/output (I/O) transmission line to propagate a signal tone. The system also includes a non-linearity circuit comprising at least one Josephson junction to provide at least one inductive path of the signal tone in parallel with the at least one Josephson junction. The system further includes an impedance matching network coupled to the I/O transmission line to provide impedance matching of the tone signal between the I/O transmission line and the non-linearity element.

A four-wave mixing transmission line (3) including: an input (15, 17, 19) arranged to receive: a first pump signal (7a) having a first pump frequency; a second pump signal (7b), having a second pump frequency, different to the first pump frequency; and an input signal to be amplified (5); a non-linear medium (3a) having an intrinsic dispersion relationship, the medium (3a) arranged to allow interaction between the input signal (5), the first pump signal (7a) and the second pump signal (7b), such that the input signal (5) is amplified and an idler signal (9) is generated and amplified; and a plurality of dispersion control elements (31, 33, 49), the dispersion control elements (31, 33, 49) arranged to alter the dispersion relationship of the medium (3a) to diverge from the intrinsic dispersion relationship at one or more frequencies, such that the total phase difference between the input signal, (5) the first pump signal (7a), the second pump signal (7b) and the idler signal (9) is kept at zero or substantially zero as the first pump signal (7a), the second pump signal (7b), the input signal (5) and the idler signal (9) propagate down the transmission line (3).

Techniques relate to an on-chip Josephson parametric converter. A Josephson ring modulator includes four nodes. A lossless on-chip flux line is capacitively coupled to two adjacent nodes of the four nodes of the Josephson ring modulator. The lossless on-chip flux line has an input port configured to receive a pump drive signal that couples differentially to the two adjacent nodes of the of the Josephson ring modulator. The pump drive signal thereby excites a common mode of the on-chip Josephson parametric converter.

Techniques relate to an on-chip Josephson parametric converter. A Josephson ring modulator includes four nodes. A lossless on-chip flux line is capacitively coupled to two adjacent nodes of the four nodes of the Josephson ring modulator. The lossless on-chip flux line has an input port configured to receive a pump drive signal that couples differentially to the two adjacent nodes of the of the Josephson ring modulator. The pump drive signal thereby excites a common mode of the on-chip Josephson parametric converter.

The disclosure is towards parametric amplifiers with inductive input coupling for quantum computing systems. One example aspect of the present disclosure is directed to a quantum computing system comprising a first qubit, a first measurement device, and a first amplifier. The first measurement device is configured to generate a first qubit signal corresponding to a first quantum state of the first qubit. The first amplifier is configured to amplify the first qubit signal. The first amplifier comprises a first transmission-line resonator. The first transmission-line resonator provides an inductive reactance for an electrical coupling between the first measurement device and the first amplifier. The inductive reactance for the electrical coupling enables a transmission of the first qubit signal.

The disclosure is towards parametric amplifiers with inductive input coupling for quantum computing systems. One example aspect of the present disclosure is directed to a quantum computing system comprising a first qubit, a first measurement device, and a first amplifier. The first measurement device is configured to generate a first qubit signal corresponding to a first quantum state of the first qubit. The first amplifier is configured to amplify the first qubit signal. The first amplifier comprises a first transmission-line resonator. The first transmission-line resonator provides an inductive reactance for an electrical coupling between the first measurement device and the first amplifier. The inductive reactance for the electrical coupling enables a transmission of the first qubit signal.

A communication method, apparatus, and system are provided, and belong to the field of communication technologies. The method includes: After receiving a first electromagnetic wave signal sent by a first adjacent node, a target third node performs target processing on the first electromagnetic wave signal to obtain a second electromagnetic wave signal, and sends the second electromagnetic wave signal to a second adjacent node. A first node, at least one third node, and a second node are sequentially disposed on a cable, and among these nodes, the target third node is adjacent to the first adjacent node and the second adjacent node. The target processing includes processing used to cause conjugate reversal of a spectrum of the electromagnetic wave signal.

Techniques relate to an on-chip Josephson parametric converter. A Josephson ring modulator includes four nodes. A lossless on-chip flux line is capacitively coupled to two adjacent nodes of the four nodes of the Josephson ring modulator. The lossless on-chip flux line has an input port configured to receive a pump drive signal that couples differentially to the two adjacent nodes of the of the Josephson ring modulator. The pump drive signal thereby excites a common mode of the on-chip Josephson parametric converter.