Yale University

Michel Devoret

Robert J Schoelkopf, Iii

Luigi Frunzio

Shyam Shankar

Katrina Sliwa

Anirudh Narla

Liang Jiang

Michael Hatridge

Steven M Girvin

Victor V Albert

Nicholas Frattini

Teresa Brecht

Shruti Puri

Stefan Krastanov

Chao Shen

Philip Reinhold

Alexander Grimm

Shantanu Mundhada

Xu Xiao

Jayameenakshi Venkatraman

Baleegh Abdo

Chen Wang

Yiwen Chu

Zlatko Kristev Minev

Yvonne Gao

Reinier Heeres

Rodrigo G Cortiñas

Ioan Pop

Steven Touzard

Philippe Campagne-lbarcq

Volodymyr Sivak

Nissim Ofek

W Clarke Smith

Lucas Verney

Mazyar Mirrahimi

Kyle Serniak

László J Szöcs

Serge Rosenblum

Uri Vool

Robert J Schoelkopf Iii

Robert John Schoelkopf

Robert J Schoelkopf

Laszlo J Szocs

Robert J Iii Schoelkopf

Zlatko Minev

Robert John Schoelkopf Iii

Robert John Iii Schoelkopf

Techniques are describing for designing and operating a quantum oscillator. In contrast with conventional approaches to operating a quantum oscillator, the present techniques relate to an oscillator design that has less bare nonlinearity than is conventionally thought to be necessary for efficient operation. Moreover, the oscillator may be driven at a frequency that is detuned away from the frequency at which a nonlinear oscillator is typically driven. In particular, the detuned drive frequency may be substantially different from the typical drive frequency, and furthermore may be a frequency that may be expected to produce a low coherence time without also engineering the reduced nonlinearity described above. As a result, the combination of an engineered reduced nonlinearity combined with a detuned drive may result in a well behaved oscillator with a strong effective nonlinearity that exhibits significantly longer coherence times than conventional quantum oscillators.

Driven kerr nonlinear oscillator and related systems and methods

Techniques for performing quantum information processing using an asymmetric error channel are provided. According to some aspects, a quantum information processing includes a data qubit and an ancilla qubit, the ancilla qubit having an asymmetric error channel. The data qubit is coupled to the ancilla qubit. The ancilla qubit may be driven with a stabilizing microwave field to create the asymmetric error channel.

Quantum information processing with an asymmetric error channel

Parametrically pumped four-wave mixing is a key building block for many developments in the field of superconducting quantum information processing. However, undesired frequency shifts such as Kerr, cross-Ken and Stark shifts inherent with four-wave mixing, lead to difficulties in tuning up the desired parametric processes and, for certain applications, severely limit the fidelities of the resulting operations. Some embodiments include a Josephson four-wave mixing device consisting of a SQUID transmon coupled to a half-flux biased SNAIL transmon, a.k.a. capacitively shunted flux qubit. When the two transmon have matching frequencies, an interference effect cancels the negative Kerr of the SQUID transmon with the positive Kerr of the SNAIL transmon while preserving parametric four-wave mixing capabilities.

Josephson nonlinear circuit

Techniques for quantum error correction of a multi-level system are provided and described. In some aspects, techniques for encoding a state of a multi-level quantum system include encoding a quantum information in a two-mode state of two quantum mechanical oscillators. Techniques for protecting the two-mode state against dephasing and energy loss are described.

Techniques for error correction of a logical qubit and related systems and methods

A superconducting device includes two nodes and a Josephson junction coupled between the two nodes, wherein the Josephson junction is characterized by a superconducting phase difference, &#x3c6;, wherein the superconducting device has a potential that varies as a function of the superconducting phase difference, &#x3c6;, and has a single potential well. The potential has a non-zero cubic term and quartic term is zero. The Josephson junction may be a single small Josephson junction. The superconducting device may include a superconducting ring connected between the two nodes. The superconducting ring may include a first ring portion with a plurality of large Josephson junctions connected in series. The superconducting ring may also include a second ring portion that includes the single small Josephson junction in parallel with the plurality of large Josephson junctions between the two nodes.

Superconducting nonlinear asymmetric inductive element and related systems and methods

The present application describes a waveform processor for control of quantum mechanical systems. The waveform processor may be used to control quantum systems used in quantum computation, such as qubits. According to some embodiments, a waveform processor includes a first sequencer configured to sequentially execute master instructions according to a defined order and output digital values in response to the executed master instructions, and a second sequencer coupled to the first sequencer and configured to generate analog waveforms at least in part by transforming digital waveforms according to digital values received from the first sequencer. The analog waveforms are applied to a quantum system. In some embodiments, the waveform processor further includes a waveform analyzer configured to integrate analog waveforms received from a quantum system and output results of said integration to the first sequencer.

Techniques for control of quantum systems and related systems and methods

Techniques for providing hardware-efficient fault-tolerant quantum operations are provided. In some aspects a cavity and an ancilla transmon are used to implement a quantum operation by encoding a logical qubit using more than two energy levels of the cavity, encoding information using more than two energy levels of the ancilla transmon, and creating an interaction between the cavity and the ancilla transmon that decouples at least one error type in the ancilla transmon from the cavity.

Hardware-efficient fault-tolerant operations with superconducting circuits

A wireless Josephson-junction-based amplifier is described that provides improved tunability and increased control over both a quality factor Q and participation ratio p of the amplifier. The device may be fabricated on a chip and mounted in a waveguide. No wire bonding between the amplifier and coaxial cables or a printed circuit board is needed. At least one antenna on the chip may be used to couple energy between the waveguide and wireless JBA. The amplifier is capable of gains greater than 25 dB.

Wireless Josephson bifurcation amplifier

Techniques are described in which a qubit is far off-resonantly, or dispersively, coupled to a quantum mechanical oscillator. In particular, a dispersive coupling between a physical qubit and a quantum mechanical oscillator may be selected such that control of the combined qubit-oscillator system can be realized. The physical qubit may be driven with an electromagnetic pulse (e.g., a microwave pulse) and the quantum mechanical oscillator simultaneously driven with another electromagnetic pulse, the combination of which results in a change in state of the qubit-oscillator system.

Techniques of oscillator state manipulation for quantum information processing and related systems and methods

Techniques for modifying the Josephson potential of a transmon qubit by shunting the transmon with an inductance are described. The inclusion of this inductance may increase the confined potential of the qubit system compared with the conventional transmon, which may lead to a transmon qubit that is stable at much higher drive energies. The inductive shunt may serve the purpose of blocking some or all phase-slips between the electrodes of the qubit. As a result, the inductively shunted transmon may offer an advantage over conventional devices when used for applications involving high energy drives, whilst offering few to no drawbacks in comparison to conventional devices when used at lower drive energies.

Inductively-shunted transmon qubit for superconducting circuits

According to some aspects, a method is provided of operating a system that includes a multi-level quantum system dispersively coupled to a first quantum mechanical oscillator and dispersively coupled to a second quantum mechanical oscillator, the method comprising applying a first drive waveform to the multi-level quantum system, applying one or more second drive waveforms to the first quantum mechanical oscillator, and applying one or more third drive waveforms to the second quantum mechanical oscillator.

Techniques for manipulation of two-qubit quantum states and related systems and methods

Some aspects are directed to a method of operating an apparatus, the apparatus comprising a first quantum system having a plurality of coherent quantum states, the first quantum system being coupled to a second quantum system, the method comprising providing an input energy signal to the second quantum system that stimulates energy transfer between the first quantum system and the second quantum system and that causes net dissipation of energy to be output from the second quantum system, wherein the input energy signal includes at least two components having different frequencies and each having an amplitude and a phase, and adiabatically varying the amplitude and the phase of the at least two components of the input energy signal to cause a change in one or more of the plurality of coherent quantum states of the first quantum system.

Techniques for universal quantum control of quantum coherent states and related systems and methods

According to some aspects, a quantum information system is provided that includes an ancilla qubit; a qudit coupled to the ancilla qubit, a detector configured to generate a detection result based on a quantum state of the ancilla qubit, and a driving source coupled to the qudit and the ancilla qubit and configured to apply at least one qudit driving signal to the qudit based on the detection result and at least one qubit driving signal to the qudit based on the detection result.

Generalized quantum channels

A wireless Josephson-junction-based parametric converter is described. The converter may be formed on a substrate with antennas that pump are configured to wirelessly receive pump, signal and idler frequencies and couple the received frequencies to the converter's circuitry. Capacitors may also be fabricated on the same substrate and sized to tune operation of the converter to desired frequencies. The converter may be coupled directly to microwave waveguides, and may be tuned to different signal frequencies by applying magnetic flux to the converter circuitry.

Wireless Josephson parametric converter

A low-noise directional amplifier includes a first port, a second port, a first coupler and a second coupler. The first port is coupled to a first coupler. The low-noise directional amplifier also includes at least two phase preserving amplifiers, a first phase preserving amplifier connected to the first coupler and a second coupler, and the second phase preserving amplifier connected to the first coupler and the second coupler.

Low-noise josephson junction-based directional amplifier

Growing community of inventors

New Haven, CT, United States of America

Michel Devoret