NetSquid Forum

Release 0.8

New minimum python dependency

• Raised minimal Python version to 3.6 (previously 3.5)

Major new features and improvements

Added a complete tutorial

• The new tutorial can be found in the docs.
• The tutorial builds up a teleportation protocol between Alice and Bob, and includes sections about qubit manipulation, discrete event simulation, components, composite components, quantum processor and programs and protocols. Mostly incorporated the old overview documentation.
• The final section that builds up a full working example of the things learned in the previous tutorials.
• A getting started guide gives a very brief summary of the tutorial topics.

Protocols run method now yields directly on event expressions

• The run() method of Protocol, which should return a generator, now expects yield statements to return an EventExpression instead of the AwaitCondition introduced in version 0.7 (which is now removed).
• The return value from a yield (expr = yield self.await_*) is a copy of the EventExpression that was yielded on.
  It contains information on the atomic expressions were triggered and with which events, which can be used to retrieve any results (such as messages available at the port for example).
• Protocol.await_event and Protocol.await_eventexpression are removed as they are obviated by yielding on event expressions directly.
• Renamed Protocol.await_sleep (now deprecated) to Protocol.await_timer. Timer starts when calling the method, not when yielding on the return value.
• Functionality of other Protocol.await_* methods remain unchanged.
• Added Protocol.await_program method.
• Removed AwaitCondition and all its subclasses.

Bell measurement instruction

• Added instructions.INSTR_MEASURE_BELL instruction that does Bell state measurement on two qubits.
• The instructions.IMeasure class now accepts optional meas_operators parameter, which overrides the observable parameter.
• Added instructions.IMeasureBell class (subclass of IMeasure) that defines the general measurement operators, but will use individual operations in the case of stabiliser formalism.

Minor features and improvements

QuantumProcessor

• Moved initializing of topologies from the QuantumProcessor constructor to the individual PhysicalInstruction constructor.
• The done/fail callbacks of a QuantumProcessor that are called once now automatically remove themselves to avoid an unneeded call to dismiss.

Protocols

• DataProtocol now subclasses NodeProtocol.

Components and Ports

• Added attributes notify_all_{input,output} to Port which, in contrast to the notify_next_{input,output} attributes, will ensure all input and output messages schedule an event.

Quantum memory

• The measure method of a QuantumMemory supports multi-qubit measurements if the dimensions of the measurement operators match the list of qubits given. If they don't match each qubit will be measured individually.
• The IMeasure instruction also supports multi-qubit measurements, identical to the measure method.

Qubits

• Added the qubits.ketutil module, with the specialised functions reduced_dm(), partial_trace(), reorder_ket(), ket_fidelity() for ket vectors.
• Moved all ket vector utility functions in ketstates.py (dagger(), ket2dm(), ...) to ketutil.py.
• Added reduced_dm() to dmutil.py module.
• qubitapi.fidelity() now calls QState.fidelity() instead of directly implementing the fidelity measurement, so that each QState can implement an optimized method. QState.fidelity() now also supports Ket and DM reference states.
• Improved KetState.fidelity() by avoiding the construction of an intermediary density matrix.