International Business Machines Corporation

Stefan Filipp

Nikolaj Moll

Daniel Josef Egger

Gian R Von Salis

Marc Ganzhorn

Jay Michael Gambetta

Jason Scott Orcutt

Hanhee Paik

Lev Samuel Bishop

Andreas Fuhrer

Thilo Hermann Curt Stoeferle

Andreas Fuhrer Janett

Stephan Paredes

Veeresh Vidyadhar Deshpande

Ute Drechsler

Matthias Mergenthaler

Andreas Kuhlmann

A method of an embodiment includes forming a capacitor pad for a nonlinear resonator. In an embodiment, the method includes comparing a resonance frequency of the nonlinear resonator to a target frequency to determine whether the resonance frequency falls within a range of the target frequency. A device of an embodiment includes a first capacitor pad comprising a superconducting material, the first capacitor pad configured to couple to a first end of a logic circuit element. In an embodiment, the device includes a second capacitor pad comprising a second superconducting material, the capacitor pad configured to couple to a second end of the logic circuit element. In an embodiment, the second capacitor pad includes a first portion; a second portion; and a bridge configured to electrically connect the first portion and the second portion.

Resonance frequency adjustment for fixed-frequency qubits

A quantum processing comprises n fixed-frequency quantum circuits of distinct frequencies, where n&#x2265;3. The device further comprises a frequency-tunable coupler, designed in such a manner that its frequency can be concomitantly modulated at m frequencies, where m&#x2265;2, and wherein said m frequencies correspond, each, to a difference of energy between a respective pair of quantum states spanned by the quantum circuits. The quantum circuits are, each, coupled to the tunable coupler. The method may rely on modulating the frequency of the tunable coupler concomitantly at said m frequencies. This, for example, is done so as to drive m energy transitions between connected pairs of states spanned by the quantum circuits and achieve an entangled state of the quantum circuits as a superposition of l states spanned by the quantum circuits, l&#x2265;m.

Multi-qubit entangling gate using a frequency-modulated tunable coupler

A device package includes a chip carrier having a cavity and one or more microwave waveguides configured to route signals. There is a chip including one or more pads and located within the cavity of the chip carrier. Each pad is aligned with a corresponding connector pad of a microwave waveguide of the one or more microwave waveguides of the chip carrier. At least one of the one or more pads is coupled to the connector pad of the corresponding microwave waveguide by way of an overlap capacitive coupling between the at least one pad and the aligned corresponding connector pad of the microwave waveguide.

Fast radio frequency package

A method of operating a quantum information processing apparatus is provided. This apparatus includes a structure of coupled qubits, where N&#x2265;3, wherein the structure further includes coupling elements. The coupling elements couple pairs of N qubits, wherein, at least, a portion of the qubits are connected by a respective one of the coupling elements, whereby the two qubits of each said pair are connected by a respective coupling element. A method comprises identifying a path of M qubits in the structure of coupled qubits, wherein the path extends from a first qubit to a last qubit of the N qubits. The identified path consists of M qubits and M&#x2212;1 coupling elements alternating along said path, where 2&#x3c;M&#x2264;N. A single-cycle operation is performed, wherein all pairs of two successive qubits in the identified path are concomitantly subjected to exchange-type interactions of distinct strengths.

Single-cycle operations using controllably mediated exchange-type interactions between qubits

Techniques relate to operating a quantum processing device is provided. The device includes at least two fixed-frequency quantum circuits coupled to a frequency-tunable coupler. The frequency of the coupler can be modulated so as to drive at least two selectively addressable energy transitions in the quantum processing device. The method includes modulating the frequency of the coupler so as to drive two first-order energy transitions. This is done so as to transfer (at least partly) an excitation of one of the quantum circuits to at least another one of the quantum circuits, via the tunable coupler. Related quantum processing devices are also provided.

Fast quantum gates with first-order transitions via frequency-modulated tunable coupling element

Embodiments are directed to a superconducting microwave circuit. The circuit includes a substrate and two electrodes. The latter form an electrode pair dimensioned so as to support an electromagnetic field, which allows the circuit to be operated in the microwave domain. The substrate exhibits a raised portion, which includes a top surface and two lateral surfaces. The top surface connects the two lateral surfaces, which show respective undercuts (on the lateral sides of the raised portions). Each of the electrodes includes a structure that includes a potentially superconducting material. Two protruding structures are accordingly formed, which are shaped complementarily to the respective undercuts. This way, the shaped structure of each of the electrodes protrudes toward the other one of the electrodes of the pair.

Buried electrode geometry for lowering surface losses in superconducting microwave circuits

Various embodiments provide a coupling mechanism, method of activation and a square lattice. The coupling mechanism comprises two qubits and a tunable coupling qubit that activates an interaction between the two qubits by modulation of a frequency of the tunable coupling qubit. The tunable coupling qubit capacitively couples the two qubits. The tunable coupling qubit is modulated at a difference frequency of the two qubits. The difference frequency may be significantly larger than an anharmonicity of the two qubits. The tunable coupling qubit may be coupled to the two qubits by two electrodes separated by a superconducting quantum interference device (SQUID) loop having two Josephson junctions or by a single electrode with a SQUID loop coupling to ground. The SQUID loop is controlled by an inductively-coupled flux bias line positioned at the center of the tunable coupling qubit.

Multi-qubit tunable coupling architecture using fixed-frequency superconducting qubits

A method for operating a quantum processing device is provided including at least two quantum circuits coupled to a tunable coupler, wherein the quantum circuits are subject to cross-talk, the method including: applying a primary signal to the quantum circuits so as to drive one or more energy transitions between states spanned by the quantum circuits; and applying a compensation signal to the tunable coupler, the compensation signal designed so as to shift at least one state spanned by the quantum circuits, in energy, to compensate for cross-talk between the quantum circuits. Related quantum processing devices and chips are also provided.

Cross-talk compensation in quantum processing devices

Transducers and methods of making the same include a substrate having a cavity with a diameter that supports whispering gallery modes at a frequency of an input signal. A focusing structure in the cavity focuses the electric field of the input signal. A resonator directly under the focusing structure has a crystalline structure that generates an electro-optic effect when exposed to electrical fields. An electric field of the input signal modulates an output signal in the resonator via the electro-optic effect.

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Zurich, Switzerland

Stefan Filipp