Qiskit Aqua 0.6.0

Changelog

Added

• Relative-Phase Toffoli gates rccx (with 2 controls) and rcccx
  (with 3 controls).
• Variational form RYCRX
• A new 'basic-no-ancilla' mode to mct.
• Multi-controlled rotation gates mcrx, mcry, and mcrz as a general
  u3 gate is not supported by graycode implementation
• Chemistry: ROHF open-shell support
  • Supported for all drivers: Gaussian16, PyQuante, PySCF and PSI4
  • HartreeFock initial state, UCCSD variational form and two qubit reduction for
    parity mapping now support different alpha and beta particle numbers for open
    shell support
• Chemistry: UHF open-shell support
  • Supported for all drivers: Gaussian16, PyQuante, PySCF and PSI4
  • QMolecule extended to include integrals, coeffiecients etc for separate beta
• Chemistry: QMolecule extended with integrals in atomic orbital basis to facilitate common access
  to these for experimentation
  • Supported for all drivers: Gaussian16, PyQuante, PySCF and PSI4
• Chemistry: Additional PyQuante and PySCF driver configuration
  • Convergence tolerance and max convergence iteration controls.
  • For PySCF initial guess choice
• Chemistry: Processing output added to debug log from PyQuante and PySCF computations (Gaussian16
  and PSI4 outputs were already added to debug log)
• Chemistry: Merged qiskit-chemistry to this repo. The old chemistry changelog is at
  OLD_CHEMISTRY_CHANGELOG.md
• Add MatrixOperator, WeightedPauliOperator and TPBGroupedPauliOperator class. (#593)
• Add evolution_instruction function to get registerless instruction of time evolution. (#593)
• Add op_converter module to unified the place in charge of converting different types of operators. (#593)
• Add Z2Symmetries class to encapsulate the Z2 symmetries info and has helper methods for tapering an
  Operator. (#593).
• Amplitude Estimation: added maximum likelihood postprocessing and confidence interval computation.
• Maximum Likelihood Amplitude Estimation (MLAE): Implemented new algorithm for amplitude estimation based on
  maximum likelihood estimation, which reduces number of required qubits and circuit depth.
• Added (piecewise) linearly and polynomially controlled Pauli-rotation circuits.
• Add q_equation_of_motion to study excited state of a molecule, and add two algorithms to prepare the reference
  state. (#655)

Changed

• Improve mct's 'basic' mode by using relative-phase Toffoli gates to build intermediate results.
• Adapt to Qiskit Terra's newly introduced Qubit class.
• Prevent QPE/IQPE from modifying input Operators.
• The PyEDA dependency was removed;
  corresponding oracles' underlying logic operations are now handled by SymPy.
• Refactor the Operator class, each representation has its own class MatrixOperator,
  WeightedPauliOperator and TPBGroupedPauliOperator. (#593)
• The power in evolution_instruction was applied on the theta on the CRZ gate directly,
  the new version repeats the circuits to implement power. (#593)
• CircuitCache is OFF by default, and it can be set via environment variable now
  QISKIT_AQUA_CIRCUIT_CACHE. (#630)

Fixed

• A bug where TruthTableOracle would build incorrect circuits for truth tables with only a single 1 value.
• A bug caused by PyEDA's indeterminism.
• A bug with QPE/IQPE's translation and stretch computation.
• Chemistry: Bravyi-Kitaev mapping fixed when num qubits was not a power of 2
• Setup initial_layout in QuantumInstance via a list. (#630)

Removed

• General multi-controlled rotation gate mcu3 is removed and replaced by
  multi-controlled rotation gates mcrx, mcry, and mcrz

Deprecated

• The Operator class is deprecated, in favor of using MatrixOperator,
  WeightedPauliOperator and TPBGroupedPauliOperator. (#593)