International Business Machines Corporation

Marcel A Kossel

Thomas E Morf

Pier Andrea Francese

Pradeep Thiagarajan

Daihyun Lim

Martin L Schmatz

Thomas Helmut Toifl

Abdullah Serdar Yonar

Jonas R Weiss

Mridula Prathapan

Hayden C Cranford, Jr

Matthias Braendli

Giovanni Cherubini

Roy Daron Cideciyan

Simeon Furrer

Peter Mueller

Christian I Menolfi

Hazar Yüksel

Michael Anthony Sorna

Vernon Roberts Norman

Alessandro Cevrero

Ilter Özkaya

Vishal Khatri

Silvan Wehrli

John Francis Bulzacchelli

Troy James Beukema

Glen Arthur Wiedemeier

Timothy O Dickson

Cezar Bogdan Zota

Shiu Chung Ho

Rafael Blanco

Martin Cochet

Zeynep Toprak-Deniz

Bogdan Cezar Zota

Sarveswara Bade

Provided is a low noise amplifier circuit for a quantum computer. The low noise amplifier circuit comprises a plurality of input stages, a shared output stage, and a voltage controller. Each input stage is coupled to one or more qubits. The shared output stage is coupled to the plurality of input stages. The voltage controller is coupled to the plurality of input stages and the shared output stage. The voltage controller is configured to selectively activate an input stage of the plurality of input stages in order to read a qubit coupled to the input stage.

Parallelized low noise amplifiers for a quantum computer

The invention is notably directed to a voltage-to-time converter comprising a first interleaving stage configured to perform a sampling of an input voltage, thereby generating a first set of sampled voltage signals. The first interleaving stage is further configured to perform a first voltage-to-time conversion in an interleaved manner, thereby generating a first set of time-interleaved signals in the time domain. A second interleaving stage is configured to perform a time-to-voltage conversion of the first set of time-interleaved signals, thereby generating a second set of sampled voltage signals. The second interleaving stage is further configured perform a second voltage-to-time conversion in an interleaved manner, thereby generating a second set of time-interleaved signals in the time domain. The invention further concerns a related design structure and a related method.

Time domain interleaving

An apparatus comprises one or more A-type resistance segments, wherein each A-type resistance segment comprises one or more A-type switches, at least one A-type linear resistor coupled to the one or more A-type switches, at least one A-type tunable header unit coupled to the one or more A-type switches, and at least one A-type tunable footer unit coupled to the one or more A-type switches; one or more B-type resistance segments, wherein each B-type resistance segment comprises one or more B-type switches, at least one B-type linear resistor coupled to at least a proper subset of the one or more B-type switches, at least one B-type tunable header unit coupled to the one or more B-type switches, and at least one B-type tunable footer unit coupled to the one or more B-type switches; and wherein second terminals of the A-type linear resistors and the B-type linear resistors are coupled together.

Segmented digital-to-analog converter wireline driver

A successive-approximation analog-to-digital converter includes a sampling circuit for sampling an analog input signal to acquire a sampled voltage, and a regenerative comparator for comparing the sampled voltage with a succession of reference voltages to generate, for each reference voltage, a decision bit indicating the comparison result. The converter also includes a digital-to-analog converter which is adapted to generate the succession of reference voltages, in dependence on successive comparison results in the comparator, to progressively approximate the sampled voltage. The regenerative comparator comprises an integration circuit for generating output signals defining the decision bits, and a plurality of regeneration circuits for receiving these output signals. The regeneration circuits are operable, in response to respective control signals, to store respective decision bits defined by successive output signals from the integration circuit.

Successive-approximation analog-to-digital converters

A hierarchical time step generator circuit is configured to be used for a time-based analog-to-digital converter. The hierarchical time step generator is configured to generate multiphase clock signals in response to receiving a reference clock signal. The time-based analog-to-digital converter is configured to be controlled to digitize the input signal by the multiphase clock signals. The hierarchical time step generator includes a first level time step generator configured to generate the a set of first level multiphase signals in response to receiving the reference clock signal a phase interpolator circuit configured as second level to generate second level clock signals between each of the first level clock signals and a third level configured to generate the third set of multiphase clock signals using a set of time staggered multi-phase phase locked loops synchronized to each of the second level clock signals.

Sampling circuit with a hierarchical time step generator

The invention relates to a control unit for controlling a data transfer between a classical processor and a quantum processor with a plurality of qubits. The control unit comprises a plurality of control and read-out circuits configured for controlling and reading out the plurality of qubits. Each of the control and read-out circuits is assigned to one or more of the qubits. A controlling of the quantum processor by the control unit comprises selectively powering on a subset of the control and read-out circuits during an instruction cycle, while ensuring that the remaining control and read-out circuits are powered off during the instruction cycle. The powered-on subset of control and read-out circuits is used to control a subset of the qubits and to read out data from the subset of qubits.

Control unit for qubits

Disclosed herein is an analog-to-digital converter circuit configured for digitizing an analog input signal. The analog-to-digital converter comprises an analog input configured for receiving the analog input signal. The analog-to-digital converter circuit further comprises at least one sub-ADC connected to the analog input signal, wherein the at least one sub-ADC is configured to output at least one encoded output vector in response to receiving the analog input signal. The analog-to-digital converter circuit further comprises a lookup circuit comprising a nested lookup table. The lookup circuit is configured to select an output value from the nested lookup table using the at least one encoded output vector, wherein the lookup circuit is configured to provide the output value as the digitization of the analog input signal.

Analog-to-digital converter circuit with a nested look up table

Systems and methods directed to a quantum processing apparatus are provided. The apparatus comprises M solid-state qubits, where M&#x3e;1, and control electronics, which are connected to the solid-state qubits. The control electronics comprise one or more qubit readout circuits, where each of the qubit readout circuits is connected to at least one of the solid-state qubits and comprises a downsampling analog-to-digital converter (hereafter DSADC). Each DSADC is configured to downsample analog signals obtained from the at least one of the solid-state qubits. Such a DSADC operates in the nNyquist zone of the spectrum of the analog signals obtained, so as to down-convert such analog signals from the nNyquist zone to the mNyquist zone of the spectrum, where n&#x3e;m&#x2265;1, prior to sampling the analog signals to convert them into digital signals, in operation. One or more embodiments of the invention are further directed to a related method of operating such a quantum processing apparatus.

Quantum processing apparatus with downsampling analog-to-digital converter

A synchronous divider circuit with time-synchronized outputs. The synchronous divider circuit includes a plurality of divider stages including each a D-flip-flop circuit and a respective retiming flip-flop circuit, wherein an output terminal of the retiming flip-flop circuit of a current divider stage is connected to an input of the D-flip-flop circuit of a next divider stage, and wherein the current divider stage includes an additional retiming flip-flop circuit, wherein the output terminal of the retiming flip-flop circuit of the current divider stage is connected to an input terminal of the additional retiming flip-flop circuit of the current divider stage, so that an output signal of the additional retiming flip-flop circuit of the current divider stage and an output terminal of the retiming flip-flop circuit of the next divider stage are time-synchronized with respect to each other.

Synchronous divider based on cascaded retiming

Methods and apparatus are provided for calculating branch metrics, associated with possible transitions between states of a trellis, in a sequence detector for detecting symbol values corresponding to samples of an analog signal transmitted over a channel. For each sample and each transition, the method calculates a plurality of distance values indicative of distance between that sample and respective hypothesized sample values for that transition. In parallel with calculation of the distance values, the sample is compared with a set of thresholds, each defined between a pair of successive hypothesized symbol values arranged in value order, to produce a comparison result. An optimum distance value is selected as a branch metric for the transition in dependence on the comparison result.

Sequence detection

A method of operating a wireline receiver. The receiver may include a front-end comparator and a feedback controller. The method may include providing, by the front-end comparator, a symbol signal by processing a received electrical input signal according to a tunable timing characteristic of the front-end comparator. The method may further include adapting, by the feedback controller, the processing of the input signal to match a predetermined processing criterion by tuning the timing characteristic based on the symbol signal.

Operating a wireline receiver with a tunable timing characteristic

The present disclosure relates to a method for quadrature error correction using a frequency divider circuit. The method comprises delaying input of data to master input terminals and/or slave input terminals of the frequency divider circuit for correcting a quadrature error between the in-phase and quadrature-phase output signals.

Clock divider with quadrature error correction

A receiver circuit is configured to receive input signals having a first reference voltage level. The first reference voltage level is a first logical high voltage level. The receiver circuit comprises an input stage comprising a resistive voltage divider. The resistive voltage divider is configured to convert the input signals having the first reference voltage level to input signals having a second reference voltage level. The second reference voltage level is a second logical high voltage level. The receiver circuit comprises a preamplifier configured to receive and amplify the input signals having the second reference voltage level.

Memory receiver with resistive voltage divider

A system and method for a high-speed transmitter comprising a precoder configured to receive a sequence of input symbols and to generate for each received symbol a respective recoded symbol is disclosed. The transmitter includes a recoding unit configured for recoding each current received PAM-M based on the recoded symbol immediately preceding the current recoded symbol at the recoding unit, a shift unit configured for determining a shift value for each current received symbol from the recoding unit based on the symbol received from the recoding unit and immediately preceding the current symbol at the shift unit; and Feed-Forward Equalizer unit for applying the shift values to the respective symbols received from the recoding unit to generate a corresponding sequence of output symbols to be transmitted in an output stream.

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Reichenburg, Switzerland

Marcel A Kossel