Abstract: Aspects of the present disclosure describe techniques for fast stabilization of multiple controller beams with continuous integrating filter. For example, a method is described for intensity stabilization of laser beams (e.g., ion controller beams) in a trapped ion system, where the method includes applying a linear array of laser beams to respective ions in a linear array of ions in a trap, performing, in response to the laser beams being applied, parallel measurements on the ions, the parallel measurements including multiple, separate measurements on each of the ions to identify fluctuations in intensity in the respective laser beams at each ion, and adjusting the intensity of one or more of the laser beams in response to fluctuations being identified from the parallel measurements. A corresponding system for intensity stabilization of laser beams in a trapped ion system is also described.

Abstract: Aspects of the present disclosure relate generally to systems and methods for use in the implementation and/or operation of quantum information processing (QIP) systems, and more particularly, to the use of deflectors in trapped ion QIP systems for individually addressing long ion chains. Methods are described for using acousto-optic deflectors (AODs) in optical Raman transitions to implement single-qubit gates and two-qubit gates. A QIP system is also described that is configured to use AODs in optical Raman transitions to implement single-qubit gates and two-qubit gates.

Abstract: The disclosure describes various techniques to control of small angle Mølmer-Sørensen (MS) gates and to handle asymmetric errors. A technique is described for handling asymmetric errors in quantum information processing (QIP) systems. An exemplary method includes implementing a quantum circuit in the QIP system that has first and second qubit lines, with a first qubit state having a greater measurement error than a second qubit state; swapping the roles of the first and second qubit states at a quantum circuit level in response to at least one of the first qubit line and the second qubit line being expected to be at the first qubit state at a measurement; and enabling a quantum simulation using the quantum circuit with the first and second qubit states reassigned in at least one of the first qubit line and the second qubit line after the swapping of the respective roles.

Abstract: Aspects of the present disclosure describe techniques for fast stabilization of multiple controller beams with continuous integrating filter. For example, a method is described for intensity stabilization of laser beams (e.g., ion controller beams) in a trapped ion system, where the method includes applying a linear array of laser beams to respective ions in a linear array of ions in a trap, performing, in response to the laser beams being applied, parallel measurements on the ions, the parallel measurements including multiple, separate measurements on each of the ions to identify fluctuations in intensity in the respective laser beams at each ion, and adjusting the intensity of one or more of the laser beams in response to fluctuations being identified from the parallel measurements. A corresponding system for intensity stabilization of laser beams in a trapped ion system is also described.

Abstract: The disclosure describes various techniques to control of small angle Mølmer-Sørensen (MS) gates and to handle asymmetric errors. A technique is described that implements a two-qubit calibration circuit with two MS gates, where a parameter ? represents an amount of entanglement of the MS gate. The calibration circuit is run for several values of ? to measure observed parity signals that are direct measurements of the values of ?. Calibration information is generated that describes the relationship between ? and the parity signals, and such calibration information is then provided to arbitrarily calibrate one or more MS gates in a quantum simulation. Another technique is described for using the calibration information in quantum simulations, including for quantum chemistry simulations.

Abstract: The disclosure describes various techniques to control of small angle Mølmer-Sørensen (MS) gates and to handle asymmetric errors. A technique is described that implements a two-qubit calibration circuit with two MS gates, where a parameter ? represents an amount of entanglement of the MS gate. The calibration circuit is run for several values of ? to measure observed parity signals that are direct measurements of the values of ?. Calibration information is generated that describes the relationship between ? and the parity signals, and such calibration information is then provided to arbitrarily calibrate one or more MS gates in a quantum simulation. Another technique is described for using the calibration information in quantum simulations, including for quantum chemistry simulations.

Abstract: The use of multiple ion chains in a single ion trap for quantum information processing (QIP) systems is described. Each chain can have its own set of laser beams with which to implement and operate quantum gates within that chain, where each chain may therefore correspond to a single quantum computing register or core. Operations can be performed in parallel across all of these chains as they can be treated independently from each other. To implement and operate quantum gates between different chains, neighboring chains are merged into a single, larger chain, in which one can perform quantum gates between any of the ions in the larger chain. The combined chains can then be separated again by another shuttling event as needed. To implement and operate quantum gates between ions which do not occupy neighboring chains, swap gates can be used via a sequence of intervening chains.

Abstract: Aspects of the present disclosure describe techniques for measuring collision rate with spatial filtering of scattered light. For example, a method for characterizing vacuum in a chamber is described that includes generating, inside the chamber, a potential well having a single, shallow potential region within which an ion is trapped, the shallow potential region having a lowest potential of the potential well, optically monitoring the ion within the potential well, detecting, based on the optically monitoring, a movement of the ion away from the shallow potential region in response to a collision with a background gas, and determining a pressure inside the chamber based on a rate of detected movements of the ion.

Abstract: The disclosure describes various techniques to control of small angle Mølmer-Sørensen (MS) gates and to handle asymmetric errors. A technique is described for handling asymmetric errors in quantum information processing (QIP) systems. An exemplary method includes implementing a quantum circuit in the QIP system that has first and second qubit lines, with a first qubit state having a greater measurement error than a second qubit state; swapping the roles of the first and second qubit states at a quantum circuit level in response to at least one of the first qubit line and the second qubit line being expected to be at the first qubit state at a measurement; and enabling a quantum simulation using the quantum circuit with the first and second qubit states reassigned in at least one of the first qubit line and the second qubit line after the swapping of the respective roles.

Abstract: Aspects of the present disclosure describe techniques for measuring collision rate with spatial filtering of scattered light. For example, a method for characterizing vacuum in a chamber is described that includes generating, inside the chamber, a potential well having a single, shallow potential region within which an ion is trapped, the shallow potential region having a lowest potential of the potential well, optically monitoring the ion within the potential well, detecting, based on the optically monitoring, a movement of the ion away from the shallow potential region in response to a collision with a background gas, and determining a pressure inside the chamber based on a rate of detected movements of the ion.

Abstract: A method of performing a computational process using a quantum computer includes generating a laser pulse sequence comprising a plurality of laser pulse segments used to perform an entangling gate operation on a first trapped ion and a second trapped ion of a plurality of trapped ions that are aligned in a first direction, each of the trapped ions having two frequency-separated states defining a qubit, and applying the generated laser pulse sequence to the first and second trapped ions. Each of the plurality of laser pulse segments has a pulse shape with ramps formed using a spline at a start and an end of each of the plurality of laser pulse segments.

Abstract: Aspects of the present disclosure describe techniques for fast stabilization of multiple controller beams with continuous integrating filter. For example, a method is described for intensity stabilization of laser beams (e.g., ion controller beams) in a trapped ion system, where the method includes applying a linear array of laser beams to respective ions in a linear array of ions in a trap, performing, in response to the laser beams being applied, parallel measurements on the ions, the parallel measurements including multiple, separate measurements on each of the ions to identify fluctuations in intensity in the respective laser beams at each ion, and adjusting the intensity of one or more of the laser beams in response to fluctuations being identified from the parallel measurements. A corresponding system for intensity stabilization of laser beams in a trapped ion system is also described.

Abstract: A method of performing a computational process using a quantum computer includes generating a laser pulse sequence comprising a plurality of laser pulse segments used to perform an entangling gate operation on a first trapped ion and a second trapped ion of a plurality of trapped ions that are aligned in a first direction, each of the trapped ions having two frequency-separated states defining a qubit, and applying the generated laser pulse sequence to the first and second trapped ions. Each of the plurality of laser pulse segments has a pulse shape with ramps formed using a spline at a start and an end of each of the plurality of laser pulse segments.

Abstract: A method of performing a computational process using a quantum computer includes generating a laser pulse sequence comprising a plurality of laser pulse segments used to perform an entangling gate operation on a first trapped ion and a second trapped ion of a plurality of trapped ions that are aligned in a first direction, each of the trapped ions having two frequency-separated states defining a qubit, and applying the generated laser pulse sequence to the first and second trapped ions. Each of the plurality of laser pulse segments has a pulse shape with ramps formed using a spline at a start and an end of each of the plurality of laser pulse segments.

Abstract: A method of performing a computational process using a quantum computer includes generating a laser pulse sequence comprising a plurality of laser pulse segments used to perform an entangling gate operation on a first trapped ion and a second trapped ion of a plurality of trapped ions that are aligned in a first direction, each of the trapped ions having two frequency-separated states defining a qubit, and applying the generated laser pulse sequence to the first and second trapped ions. Each of the plurality of laser pulse segments has a pulse shape with ramps formed using a spline at a start and an end of each of the plurality of laser pulse segments.

Abstract: The disclosure describes various techniques to control of small angle Mølmer-Sorensen (MS) gates and to handle asymmetric errors. A technique is described that implements a two-qubit calibration circuit with two MS gates, where a parameter ? represents an amount of entanglement of the MS gate. The calibration circuit is run for several values of ? to measure observed parity signals that are direct measurements of the values of ?. Calibration information is generated that describes the relationship between ? and the parity signals, and such calibration information is then provided to arbitrarily calibrate one or more MS gates in a quantum simulation. Another technique is described for using the calibration information in quantum simulations, including for quantum chemistry simulations.

Abstract: A method of performing an entangling operation in a chain of trapped ions includes selecting a gate duration value and a detuning value of a pulse sequence used to perform an entangling gate operation on a first ion and a second ion, measuring frequencies of collective motional modes of the chain, computing a value of an entangling interaction between the first and second ions and values of phase space trajectories of the collective motional modes, based on the selected gate duration value, the selected detuning value, and the measured frequencies of the collective motional modes, determining an intensity of each pulse segment in the pulse sequence based on the computed values, generating the pulse sequence by connecting the pulse segments, each pulse segment having the determined intensity and a pulse shape with ramps formed using a spline, and applying the generated pulse sequence to the first and second ions.