System Requirements

Compiling & Source Code

Starting the Simulator

• interactive mode the interactive mode provides a graphical user interface for the design and test of quantum circuits.

To start the simulator in this mode issue the following command:

                        java -jar jaQuzzi.jar

or access the embedded version on

 http://www.physics.buffalo.edu/~phygons/jaQuzzi/jaQuzzi/applet.html




• batch mode the batch mode allows to run a simulation of a circuit from the command line without graphical output. This mode can be used to automize quantum calculations.

Interactive Mode

Building a Circuit
A circuit can be thought of being arranged in rows and columns of a table. Each row represents a qubit, each column a gate operation. To setup a gate operation to a certain qubit simply create a new gate column, select the corresponding qubit cell in this column an make a right mouse click. The program uses different ways to translate the user selection into an adequate gate (see specify gate).
For the purpose of building more complex circuits and controlling simulation properties locally, gates can be grouped into gate groups. Gates within gate groups cannot be changed unless ungrouped.

• add/remove qubit a right mouse click on the qubit area on the left hand side reveals a popup menu which allows to add/insert or remove a qubit. The qubit over which the click occured is affected.
• add/remove gate a right mouse click on the gate headers reveals a popup menu with functionality for gate management, such as add/insert or remove. Selected gates are affected.
• specify gate a right click on the gate area reveals a popup menu where different kinds of gates can be chosen. There are basically three different ways of how the program translates a qubit selection into a gate:
1. controllable gates. The first section in the popup menu allows to generate controlled gates. Depending on the number of qubits selected and the dimension of the chosen gate operation, remaining qubits are assigned as control qubits.

example 1 two selected qubits and the NOT gate make the other selected qubit a control qubit
example 2 two selected qubits and a 2-qubit gate just generate the 2-qubit gate
The order of the selection determines which of the qubits are controlling and which are controlled. The qubits selected last are the controlled qubits.
example 3 a left click on the first qubit and dragging the mouse down to the last qubit and then choosing the NOT gate creates a multiple controlled NOT gate operating on the last qubit
example 4 a left click on the first qubit, a CTRL-left click on the last qubit and a CTRL-left click to a middle qubit in combination with the NOT gate generates a NOT gate operating on the middle qubit controlled by the first and last qubit
2. variable size gates. The middle section in the popup menu contains gates which are variable in size. This does not mean that the gates themselves are variable in size, rather instead of filling controll qubits in, the gates are applied to all the selected qubits.

example 5 selecting all qubits and choosing the Hadamard gate will apply the single-qubit Hadamard operation to all qubits
example 6 selecting all qubits and choosing QFT will generate a Fourier transform of the given number of qubits
Since only one gate per column can be applied, sometimes additional columns need to be added (this is done automatically).
3. fixed size gates. The last section in the popup menu holds gates which only apply to a fixed number of qubits, such as the exchange gate or predefined templates (right now only a compare circuit is implemented).
• grouping gates In order to group gates select the gate columns by pressing CTRL or SHIFT and left clicking on the gate headers. Click right on the selected headers and choose group. Single gates in a gate group cannot be modiefied unless ungrouped. Gate properties overwrite group properties which again overwrite circuit properties. To ungroup simply click right and select ungroup. During ungrouping it might be necessary to rename gates to avoid name conflicts. This is handled automatically by the program.
• controlling properties single gates/gate groups can have additional properties such as name, repetition or settings for the simulation. The properties are accessed with a right mouse click on the gate header under 'properties'. Global simulation properties are accessed by the button on the left hand side of the info panel in the toolbar.

• Initialization with a single click on a qubit arrows on the left hand side, a qubit can be initialized to spin up or spin down. Superpositions are generated with gate operations.
• Reset the simulation can be reset by either initializing a qubit or clicking on the left arrow in the simulation control panel.
• Stepping the simulation can be performed step by step or in whole. To step through the circuit use the left/right symbols in the simulation control panel.
• Running to automatically step through the whole circuit use the button with the zeros and ones in the simulation control panel. The simulation can be stopped by pressing the same button again.
• Measurement the simulation control panel provides a button for performing a complete measurement. Partial measurements are implemented via measurement gates within a circuit.

• info panel the info panel is located in the toolbar and provides general information for the progress of the computation. Clicks on the info panel reveal different information (such as, average time per gate operation, estimated remaining time, etc.).
• chart center the chart center allows to display probability distribution, phases and the fidelity of a computation for any choice of qubits. To specify the qubits to display just select the qubits in the gate area and press the chart button in the toolbar. The char center allows automatic refresh (which can be computationally expensive and therefore is not activated upon start-up) to follow computations. It is possible to save the probability distribution and fidelity into a file which can be processed with the GNUplot program. For that simply load the generated files (the naming convention is 'circuitname+number+.fid/prob') with the command ``load'' into GNUplot.
• data center the data center allows to display numerical values of the probability distribution, phases and fidelity. Since the data center usually is accessed through the chart center, it uses the same qubit selection. When the data center is called with the enlarge button right next to the state vector information row in the main window, all qubits are seclected.

Batch Mode

The following options are implemented:

• -mode simMode This option allows it to explicitly set the simulation mode. Possible values for simMode are: 0 = ideal simulation, 1 = operational errors only, 2 = decoherence errors only, 3 = operational and decoherence errors. If this option is not specified, the simulation mode is determined from the simulation properties saved in the circuit file, or if `-sigma', `-rate' or `-decay' is specified, a mode is chosen to accomodate the parameters (e.g., if only `-sigma' is specified, mode 1 is chosen).
• -init bitString This option allows to initialize the qubit ket to a specified basis ket. The bitString needs to have the same length as numbers of qubits in the circuit. E.g., `-init 010' initializes a 3-qubit circuit to the ket |010>.
• -plot bitString This option allows to specify the qubits that are plotted in the probability distribution. This is useful for circuit where the Fourier qubits are of interest and not necessarily the other work qubits. The bitString needs to have the same length as numbers of qubits in the circuit. E.g., `-plot 011' outputs the probability distribution of the two lowest order qubits.
• -sigma start:end:steps:reps This option allows it to vary the standard deviation sigma which controls the noise error. Not all values need to be specified. E.g., `-sigma 0.01:::5' causes 5 repetitive runs with sigma=0.01, `-sigma 0.01:0.02' will cause 2 runs, one with sigma=0.1 and one with sigma=0.02. If this option is given without `-mode', `-rate' or `-decay', the simulation mode is automatically set to 1.
• -rate start:end:steps:reps This option allows it to vary the error rate per gate which controls the decoherence error. Not all values need to be specified. E.g., `-rate 0.001:0.002:3' causes 3 runs, one with rate=0.01, one with rate=0.0015 and the last with rate=0.002. If the option `-decay' is not specified, first the properties of the circuit are checked. If there is no decay probability specified, either, a decay probability of p=0.5 is assumed. If the `-rate' option is given without `-mode' or `-sigma', the simulation mode is automatically set to 2.
• -decay start:end:steps:reps This option allows it to vary the decay probability in case of a decoherence event. Not all values need to be specified. E.g., `-decay 0.6' just sets the decay probability to p=0.6. If the option `-decay' is specified without the option `-rate', the circuit properties are checked. If there is no decoherence rate given, either, the decoherence rate is set to 10^{-4}. If the `-decay' option is given without `-mode' or `-sigma', the simulation mode is automatically set to 2.