Quantum Valley Investment Fund LP

Schlumberger Technology Corporation

Troy W Borneman

David G Cory

Hamidreza Mohebbi

Ian N Hincks

Donald Edward Carkner

Christopher James Wood

Chris E Granade

Soumyajit Mandal

Martin D Hürlimann

Derek Blair Poirier Thompson

Van D M Koroleva

Christopher E Granade

Wei-Lin Ou

Andrew Boorn

In a general aspect, a magnetic resonance system is operated. In some examples, an amplifier circuit for a magnetic resonance system includes first and second switch devices, a high-power amplifier (HPA) device, and a power combiner device. The first switch device includes an input port and two output ports. The HPA device includes an HPA input port and an HPA output port. The HPA input port is coupled to a first output port of the first switch device. The second switch device includes input and output ports. The power combiner device includes two input ports and an output port. A first input port of the power combiner device is coupled to the output port of the second switch device. A second input port of the power combiner device is coupled to the second output port of the first switch device along a path that bypasses the HPA device.

Operating circuitry in a magnetic resonance system

In a general aspect, a sample holder has multiple sample containers. In some instances, the sample holder can be received into a resonator package in a primary magnetic field of a magnetic resonance system. The resonator package includes a resonator configured to interact with a sample in a sample region. The sample holder includes a first sample and a calibration sample. The position of the sample holder relative to the resonator is calibrated. After calibrating the position of the sample holder, the sample holder is translated to position the first sample in the sample region. Magnetic resonance data is acquired based on magnetic resonance signals generated by an interaction between the resonator and the first sample.

Changing samples in a magnetic resonance system

A method is presented for controlling a spin system in an external magnetic field. The method includes sending a first pulse to a resonator over a first period. The resonator generates a magnetic field in response to receiving the first pulse. Moreover, the resonator applies the magnetic field to the spin system and the first pulse maintains the magnetic field in a transient state during the first period. The method also includes sending a second pulse to the resonator over a second period immediately following the first period. The resonator alters a magnitude of the magnetic field to zero in response to receiving the second pulse. Other methods are presented for controlling a spin system in an external magnetic field, including systems for controlling a spin system in an external field.

Model-insensitive control of nonlinear resonators

In some aspects, a control system interacts with a quantum system. In some instances, the quantum system includes qubits that respond to a control signal generated by the control system, and the control system is configured to generate the control signal in response to an input signal. A control sequence (which may include, for example, a sequence of values for the input signal) can be generated by a computing system based on a target operation to be applied to the qubits. The control sequence can be generated based on the target operation, a quantum system model, a distortion model and possibly other information. The quantum system model represents the quantum system and includes a control parameter representing the control signal. The distortion model represents a nonlinear relationship between the control signal and the input signal. The control sequence is applied to the quantum system by operation of the control system.

Generating a control sequence for quantum control

In some aspects, polarization of a spin ensemble can be increased using cavity-based techniques. A cavity is coupled with a spin ensemble, and a drive field generates an interaction between the cavity and the spin ensemble. In some cases, the interaction increases the polarization of the spin ensemble faster than the thermal (T) relaxation process or any other thermal polarizing process affecting the spin ensemble. In some cases, polarization is increased by iteratively acting on angular momentum subspaces of the spin ensemble, and mixing the angular momentum subspaces, for example, by a dipolar interaction, a transverse (T) relaxation process, application of a gradient field, or a combination of these and other processes.

Efficient spin polarization

In some aspects, polarization of a spin ensemble can be increased using cavity-based techniques. A resonator applies drive field to a spin ensemble in a static magnetic field. The drive field couples the spin ensemble with a cavity, and the coupling increases the polarization of the spin ensemble. In some cases, the cavity is detuned from the spin- resonance frequency, and the Rabi frequency associated with the drive field can be matched to the cavity detuning.

Using a cavity to polarize a spin ensemble

A method for applying a nuclear magnetic resonance (NMR) sequence is described herein. The method includes applying a series of refocusing pulses to a substance within an inhomogeneous static magnetic field. Each refocusing pulse in the series of refocusing pulses includes a central axis, a total pulse duration greater than t, and at least five segments (e.g., 5, 7, 11, 20, and 21). The phase of each segment is substantially anti-symmetric about the central axis of the refocusing pulse. In a more particular embodiment, the phase of each segment is also symmetric about the central axis of the refocusing pulse and the five segments include a substantially constant amplitude.

Nuclear magnetic resonance refocusing pulses for inhomogeneous magnetic fields

A quantum information processor can include a control system and a system of processor nodes. Each of the processor nodes can include multiple qubits and an actuator. The control system can manipulate the qubits of multiple processor nodes based on cross-node quantum interactions between the qubits. In some instances, the control system may perform multi-qubit quantum gates on qubits of different processor nodes based on the cross-node quantum interactions. Within each processor node, the qubits interact with the actuator by an intra-node quantum coupling. Between processor nodes, the actuators interact with each other by an inter-node quantum coupling. The cross-node quantum interaction can be produced by non-commutivity of the intra-node quantum couplings and the inter-node quantum couplings. In some instances, the qubits can be manipulated by applying a control sequence that produces an interaction frame where the cross-node quantum interaction dominates the time evolution of the system.

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Waterloo, Canada

Troy W Borneman